path: root/xc/programs/Xserver/hw/xfree86/doc/README.chips

                 Information for Chips and Technologies Users

                David Bateman (<dbateman@club-internet.fr>),
                           Egbert Eich (<eich@xfree86.org>)

                                14th June 2000

1.  Introduction

With the release of XFree86 version 4.0.1, the Chips and Technologies driver
has been extensively rewritten and contains many new features.  This driver
must be considered work in progress, and those users wanting stability are
encouraged to use the older XFree86 3.3.x versions. However this version of
the Chips and Technologies driver has many new features and bug fixes that
might make users prefer to use this version. These features include

   o The long standing black/blue screen problem that some people have had
     should be fixed.

   o Hardware/Software cursor switching on the fly, that should fix many of
     the known hardware cursor problems.

   o Gamma correction at all depths and DirectColor visuals for depths of 15
     or greater with the HiQV series of chipsets.

   o Supports PsuedoColor overlays on 16bpp TrueColor screens for HiQV.

   o Supports YUV colour space conversion with the XVideo extension.

   o 32bpp pixmaps while using a framebuffer in 24bpp packed pixel mode.

   o Heaps more acceleration.

   o 1/4bpp support.

   o Multihead

   o Much more...

This document attempts to discuss the features of this driver, the options
useful in configuring it and the known problems. Most of the Chips and Tech-
nologies chipsets are supported by this driver to some degree.

2.  Supported Chips

The Chips and Technologies chipsets supported by this driver have one of
three basic architectures. A basic architecture, the WinGine architecture
which is a modification on this basic architecture and a completely new HiQV
architecture.

2.1  Basic architecture

      ct65520
            (Max Ram: 1Mb, Max Dclk: 68MHz@5V)

      ct65525
            This chip is basically identical to the 65530. It has the same ID
            and is identified as a 65530 when probed. See ct65530 for
            details.

      ct65530
            This is a very similar chip to the 65520. However it additionally
            has the ability for mixed 5V and 3.3V operation and linear
            addressing of the video memory.  (Max Ram: 1Mb, Max Dclk:
            56MHz@3.3V, 68MHz@5V)

      ct65535
            This is the first chip of the ct655xx series to support fully
            programmable clocks. Otherwise it has the the same properties as
            the 65530.

      ct65540
            This is the first version of the of the ct655xx that was capable
            of supporting Hi-Color and True-Color. It also includes a fully
            programmable dot clock and supports all types of flat panels.
            (Max Ram: 1Mb, Max Dclk: 56MHz@3.3V, 68MHz@5V)

      ct65545
            The chip is very similar to the 65540, with the addition of H/W
            cursor, pop-menu acceleration, BitBLT and support of PCI Buses.
            PCI version also allow all the BitBLT and H/W cursor registers to
            be memory mapped 2Mb above the Base Address.  (Max Ram: 1Mb, Max
            Dclk: 56MHz@3.3V,68MHz@5V)

      ct65546
            This chip is specially manufactured for Toshiba, and so documen-
            tation is not widely available. It is believed that this is
            really just a 65545 with a higher maximum dot-clock of 80MHz.
            (Max Ram: 1Mb?, Max Dclk: 80MHz?)

      ct65548
            This chip is similar to the 65545, but it also includes XRAM sup-
            port and supports the higher dot clocks of the 65546.  (Max Ram:
            1Mb, Max Dclk: 80MHz)

2.2  WinGine architecture

      ct64200
            This chip, also known as the WinGine, is used in video cards for
            desktop systems. It often uses external DAC's and programmable
            clock chips to supply additional functionally. None of these are
            currently supported within the driver itself, so many cards will
            only have limited support. Linear addressing is not supported for
            this card in the driver.  (Max Ram: 2Mb, Max Dclk: 80MHz)

      ct64300
            This is a more advanced version of the WinGine chip, with speci-
            fication very similar to the 6554x series of chips. However there
            are many differences at a register level. A similar level of
            acceleration to the 65545 is included for this driver.  (Max Ram:
            2Mb, Max Dclk: 80MHz)

2.3  HiQV Architecture

      ct65550
            This chip includes many new features, including improved BitBLT
            support (24bpp colour expansion, wider maximum pitch, etc), Mul-
            timedia unit (video capture, zoom video port, etc) and 24bpp
            uncompressed true colour (i.e 32bpp mode). Also memory mapped I/O
            is possible on all bus configurations.  (Max Ram: 2Mb, Max Dclk:
            80MHz@3.3V,100MHz@5V)

      ct65554
            This chip is similar to the 65550 but has a 64bit memory bus as
            opposed to a 32bit bus. It also has higher limits on the maximum
            memory and pixel clocks (Max Ram: 4Mb, Max Dclk: 100MHz@3.3V)

      ct65555
            Similar to the 65554 but has yet higher maximum memory and pixel
            clocks. It also includes a new DSTN dithering scheme that
            improves the performance of DSTN screens.  (Max Ram: 4Mb, Max
            Dclk: 110MHz@3.3V)

      ct68554
            Similar to the 65555 but also incorporates "PanelLink" drivers.
            This serial link allows an LCD screens to be located up to 100m
            from the video processor. Expect to see this chip soon in LCD
            desktop machines (Max Ram: 4Mb, Max Dclk: 110MHz@3.3V)

      ct69000
            Similar to the 65555 but incorporates 2Mbytes of SGRAM on chip.
            It is the first Chips and Technologies chipset where all of the
            registers are accessible through MMIO, rather than just the Bit-
            Blt registers.  (Max Ram: 2Mb Only, Max Dclk: 130MHz@3.3V)

      ct69030
            Similar to the 69000 but incorporates 4Mbytes of SGRAM on chip
            and has faster memory and pixel clock limits. Also includes a
            second display channel so that the CRT can display independently
            of the LCD.  (Max Ram: 4Mb Only, Max Dclk: 170MHz@3.3V)

3.  XF86Config Options

The following options are of particular interest to the Chips and Technolo-
gies driver. It should be noted that the options are case insensitive, and
that  white space and "_" characters are ignored.  There are therefore a wide
variety of possible forms for all options.  The forms given below are the
preferred forms.

Options related to drivers can be present in the Screen, Device and Monitor
sections and the Display subsections.  The order of precedence is Display,
Screen, Monitor, Device.

      Option "NoAccel"
            This option will disable the use of any accelerated functions.
            This is likely to help with some problems related to DRAM timing,
            high dot clocks, and bugs in accelerated functions, at the cost
            of performance (which will still be reasonable on VLB/PCI).

      VideoRam 1024 (or another value)
            This option will override the detected amount of video memory,
            and pretend the given amount of memory is present on the card.

      Option "NoLinear"
            By default linear addressing is used on all chips where it can be
            set up automatically. The exception is for depths of 1 or 4bpp
            where linear addressing is turned off by default.  It is possible
            to turn the linear addressing off with this option. Note that H/W
            acceleration is only supported with linear addressing.

      Option "Linear"
            When the chipset is capable of linear addressing and it has been
            turned off by default, this option can be used to turn it back
            on. This is useful for the 65530 chipset where the base address
            of the linear framebuffer must be supplied by the user, or at
            depths 1 and 4bpp. Note that linear addressing at 1 and 4bpp is
            not guaranteed to work correctly.

      MemBase 0x03b00000 (or a different address)
            This sets the physical memory base address of the linear frame-
            buffer. Typically this is probed correctly, but if you believe it
            to be mis-probed, this option might help.  Also for non PCI
            machines specifying this force the linear base address to be this
            value, reprogramming the video processor to suit. Note that for
            the 65530 this is required as the base address can't be correctly
            probed.

      Option "HWcursor"
            For chipsets that support hardware cursors, this option enforces
            their use, even for cases that are known to cause problems on
            some machines. Note that it is overridden by the "SWcursor"
            option. Hardware cursors effectively speeds all graphics opera-
            tions as the job of ensuring that the cursor remains on top is
            now given to the hardware. It also reduces the effect of cursor
            flashing during graphics operations.

      Option "SWcursor"
            This disables use of the hardware cursor provided by the chip.
            Try this if the cursor seems to have problems.

      Option "STN"
            The server is unable to differentiate between SS STN and TFT dis-
            plays. This forces it to identify the display as a SS STN rather
            than a TFT.

      Option "UseModeline"
            The flat panel timings are related to the panel size and not the
            size of the mode specified in XF86Config. For this reason the
            default behaviour of the server is to use the panel timings
            already installed in the chip. The user can force the panel tim-
            ings to be recalculated from the modeline with this option. How-
            ever the panel size will still be probed.

      Option "FixPanelSize"
            For some machines the LCD panel size is incorrectly probed from
            the registers. This option forces the LCD panel size to be over-
            ridden by the modeline display sizes. This will prevent the use
            of a mode that is a different size than the panel. Before using
            this check that the server reports an incorrect panel size. This
            option can be used in conjunction with the option "UseModeline"
            to program all the panel timings using the modeline values.

      Option "NoStretch"
            When the size of the mode used is less than the panel size, the
            default behaviour of the server is to stretch the mode in an
            attempt to fill the screen. A "letterbox" effect with no stretch-
            ing can be achieved using this option.

      Option "LcdCenter"
            When the size of the mode used is less than the panel size, the
            default behaviour of the server is to align the left hand edge of
            the display with the left hand edge of the screen. Using this
            option the mode can be centered in the screen. This option is
            reported to have problems with some machines at 16/24/32bpp, the
            effect of which is that the right-hand edge of the mode will be
            pushed off the screen.

      Option "HWclocks"
            For the chips either using the WinGine or basic architectures,
            the chips generates a number of fixed clocks internally. With the
            chips 65535 and later or the 64300, the default is to use the
            programmable clock for all clocks. It is possible to use the
            fixed clocks supported by the chip instead by using this option.
            Typically this will give you some or all of the clocks 25.175,
            28.322, 31.000 and 36.000MHz. The current programmable clock will
            be given as the last clock in the list. On a cold-booted system
            this might be the appropriate value to use at the text console
            (see the "TextClockFreq" option), as many flat panels will need a
            dot clock different than the default to synchronise. The pro-
            grammable clock makes this option obsolete and so it's use isn't
            recommended. It is completely ignored for HiQV chipsets.

      Option "UseVclk1"
            The HiQV series of chips have three programmable clocks. The
            first two are usually loaded with 25.175 and 28.322MHz for VGA
            backward compatibility, and the third is used as a fully pro-
            grammable clock. On at least one system (the Inside 686 LCD/S
            single board computer) the third clock is unusable. This option
            forces the use of VClk1 as the programmable clock.

      TextClockFreq 25.175
            Except for the HiQV chipsets, it is impossible for the server to
            read the value of the currently used frequency for the text con-
            sole when using programmable clocks. Therefore the server uses a
            default value of 25.175MHz as the text console clock. For some
            LCDs, in particular DSTN screens, this clock will be wrong. This
            allows the user to select a different clock for the server to use
            when returning to the text console.

      Option "FPClock8"   "65.0"
            Option "FPClock16"  "65.0" Option "FPClock24"  "65.0" Option
            "FPClock32"  "65.0"" In general the LCD panel clock should be set
            independently of the modelines supplied. Normally the chips BIOS
            set the flat panel clock correctly and so the default behaviour
            with HiQV chipset is to leave the flat panel clock alone, or
            force it to be 90% of the maximum allowable clock if the current
            panel clock exceeds the dotclock limitation due to a depth
            change. This option allows the user to force the server the
            reprogram the flat panel clock independently of the modeline with
            HiQV chipset. The four options are for 8bpp or less, 16, 24 or
            32bpp LCD panel clocks, where the options above set the clocks to
            65MHz.

      Option "MMIO"
            This has a different effect depending on the hardware on which it
            is used. For the 6554x machines MMIO is only used to talk to the
            BitBLT engine and is only usable with  PCI buses. It is enabled
            by default for 65545 machines since the blitter    can not be
            used otherwise. The HiQV series of chipsets must use MMIO with
            their BitBLT engines, and so this is enabled by default. However
            the 690xx chipsets can use MMIO for all communications with the
            video processor. So using this option on a 690xx chipset forces
            them to use MMIO for all communications. This only makes sense
            when the 690xx is on a PCI bus so that normal PIO can be dis-
            abled.  (WARNING!! 690xx MMIO is untested)

      Option "SuspendHack"
            This option sets the centering and stretching to the BIOS default
            values. This can fix suspend/resume problems on some machines. It
            overrides the options "LcdCenter" and "NoStretch".

      Option "18bitBus"  (Chips 65540/45/46/48)
            For 24bpp on TFT screens, the server assumes that a 24bit bus is
            being used. This can result in a reddish tint to 24bpp mode.
            This option, selects an 18 bit TFT bus. For other depths this
            option has no effect.

      Chipset "ct65546" (or some other chip)
            It is possible that the chip could be misidentified, particular
            due to interactions with other drivers in the server. It is pos-
            sible to force the server to identify a particular chip with this
            option.

      Option "SyncOnGreen"
            Composite sync on green. Possibly useful if you wish to use an
            old workstation monitor. The HiQV internal RAMDAC's supports this
            mode of operation, but whether a particular machine does depends
            on the manufacturer.

      DacSpeed 80.000
            The server will limit the maximum dotclock to a value as speci-
            fied by the manufacturer. This might make certain modes impossi-
            ble to obtain with a reasonable refresh rate. Using this option
            the user can override the maximum dot-clock and specify any value
            they prefer. Use caution with this option, as driving the video
            processor beyond its specifications might cause damage.

      Option "SetMClk" "38.000MHz"
            Option "SetMClk" "38000kHz"" This option sets the internal memory
            clock (MCLK) registers of HiQV chipsets to 38MHz or some other
            value. Use caution as excess heat generated by the video proces-
            sor if its specifications are exceeded might cause damage. How-
            ever careful use of this option might boost performance. This
            option might also be used to reduce the speed of the memory clock
            to preserve power in modes that don't need the full speed of the
            memory to work correctly. This option might also be needed to
            reduce the speed of the memory clock with the "Overlay" option.

      Option "RGBbits"  "8"
            By default it is assumed that there are 6 significant bits in the
            RGB representation of the colours in 4bpp and above. If the
            colours seem darker than they should be, perhaps your ramdac is
            has 8 significant bits. This option forces the server to assume
            that there are 8 significant bits.

      Option "ShowCache"
            This is a debugging option and general users have no need of it.
            Using this option, when the virtual desktop is scrolled away from
            the zero position, the pixmap cache becomes visible. This is use-
            ful to see that pixmaps, tiles, etc have been properly cached.

      Option "ShadowFB"
            This option is only useful when acceleration can't be used and
            linear addressing can be used. With this option all of the graph-
            ics are rendered into a copy of the framebuffer that is keep in
            the main memory of the computer, and the screen is updated from
            this copy. In this way the expensive operation of reading back to
            contents of the screen is never performed and the performance is
            improved. Because the rendering is all done into a virtual frame-
            buffer acceleration can not be used.

      Option "Overlay"
            The HiQV chipsets contain a multimedia engine that allow a 16bpp
            window to be overlayed on the screen. This driver uses this capa-
            bility to include a 16bpp framebuffer on top of an 8bpp frame-
            buffer. In this way PseudoColor and TrueColor visuals can be used
            on the same screen.  XFree86 believes that the 8bpp framebuffer
            is overlayed on the 16bpp framebuffer. Therefore to use this
            option the server must be started in either 15 or 16bpp depth.
            Also the maximum size of the desktop with this option is
            1024x1024, as this is the largest window that the HiQV multimedia
            engine can display. Note that this option using the multimedia
            engine to its limit, and some manufacturers have set a default
            memory clock that will cause pixel errors with this option.  If
            you get pixel error with this option try using the "SetMClk"
            option to slow the memory clock. It should also be noted that the
            XVideo extension uses the same capabilities of the HiQV chipsets
            as the Overlays. So using this option disables the XVideo exten-
            sion.

      Option "ColorKey" "255"
            Normally the colour transparency key for the overlay is the 8bpp
            lookup table entry 255. This might cause troubles with some
            applications, and so this option allows the colour transparency
            key to be set to some other value. Legal values are 2 to 255
            inclusive.

      Option "VideoKey" "255"
            This sets the default pixel value for the YUV video overlay key.
            Legal values for this key are depth dependent. That is from 0 to
            255 for 8bit depth, 0 to 32,767 for 15bit depth, etc. This option
            might be used if the default video overlay key causes problems.

      Option "XaaNoScreenToScreenCopy",
            Option "XaaNoSolidFillRect", Option "XaaNoSolidHorVertLine",
            Option "XaaNoMono8x8PatternFillRect", Option "XaaNoColor8x8Pat-
            ternFillRect", Option "XaaNoCPUToScreenColorExpandFill", Option
            "XaaNoScreenToScreenColorExpandFill", Option "XaaNoIm-
            ageWriteRect", Option "XaaNoImageReadRect", Option "XaaNoPixmap-
            Cache", Option "XaaNoOffscreenPixmaps" " These option individu-
            ally disable the features of the XAA acceleration code that the
            Chips and Technologies driver uses. If you have a problem with
            the acceleration and these options will allow you to isolation
            the problem. This information will be invaluable in debugging any
            problems.

4.  Modelines

When constructing a modeline for use with the Chips and Technologies driver
you'll needed to considered several points

      * Virtual Screen Size
            It is the virtual screen size that determines the amount of mem-
            ory used by a mode. So if you have a virtual screen size set to
            1024x768 using a 800x600 at 8bpp, you use 768kB for the mode.
            Further to this some of the XAA acceleration requires that the
            display pitch is a multiple of 64 pixels. So the driver will
            attempt to round-up the virtual X dimension to a multiple of 64,
            but leave the virtual resolution untouched. This might further
            reduce the available memory.

      * 16/24/32 Bits Per Pixel
            Hi-Color and True-Color modes are implemented in the server. The
            clocks in the 6554x series of chips are internally divided by 2
            for 16bpp and 3 for 24bpp, allowing one modeline to be used at
            all depths.  The effect of this is that the maximum dot clock
            visible to the user is a half or a third of the value at 8bpp.
            The HiQV series of chips doesn't need to use additional clock
            cycles to display higher depths, and so the same modeline can be
            used at all depths, without needing to divide the clocks.  Also
            16/24/32 bpp modes will need 2 , 3 or 4 times respectively more
            video ram.

      * Frame Acceleration
            Many DSTN screens use frame acceleration to improve the perfor-
            mance of the screen. This can be done by using an external frame
            buffer, or incorporating the framebuffer at the top of video ram
            depending on the particular implementation. The Xserver assumes
            that the framebuffer, if used, will be at the top of video ram.
            The amount of ram required for the framebuffer will vary depend-
            ing on the size of the screen, and will reduce the amount of
            video ram available to the modes. Typical values for the size of
            the framebuffer will be 61440 bytes (640x480 panel), 96000 bytes
            (800x600 panel) and 157287 bytes (1024x768 panel).

      * H/W Acceleration
            The H/W cursor will need 1kB for the 6554x and 4kb for the 65550.
            On the 64300 chips the H/W cursor is stored in registers and so
            no allowance is needed for the H/W cursor. In addition to this
            many graphics operations are speeded up using a "pixmap cache".
            Leaving too little memory available for the cache will only have
            a detrimental effect on the graphics performance.

      * PseudoColor Overlay
            If you use the "overlay" option, then there are actually two
            framebuffers in the video memory. An 8bpp one and a 16bpp one.
            The total memory requirements in this mode of operation is there-
            fore similar to a 24bpp mode. The overlay consumes memory band-
            width, so that the maximum dotclock will be similar to a 24bpp
            mode.

      * XVideo extension*
            Like the overlays, the Xvideo extension uses a part of the video
            memory for a second framebuffer. In this case enough memory needs
            to be left for the largest unscaled video window that will be
            displayed.

      * VESA like modes
            We recommend that you try and pick a mode that is similar to a
            standard VESA mode. If you don't a suspend/resume or LCD/CRT
            switch might mess up the screen. This is a problem with the video
            BIOS not knowing about all the funny modes that might be
            selected.

      * Dot Clock
            For LCD screens, the lowest clock that gives acceptable contrast
            and flicker is usually the best one. This also gives more memory
            bandwidth for use in the drawing operations. Some users prefer to
            use clocks that are defined by their BIOS. This has the advantage
            that the BIOS will probably restore the clock they specified
            after a suspend/resume or LCD/CRT switch. For a complete discus-
            sion on the dot clock limitations, see the next section.

The driver is capable of driving both a CRT and a flat panel display. In fact
the timing for the flat panel are dependent on the specification of the panel
itself and are independent of the particular mode chosen. For this reason it
is recommended to use one of the programs that automatically generate
XF86Config files, such as "xf86config" or "XF86Setup".

However there are many older machines, particularly those with 800x600 screen
or larger, that need to reprogram the panel timings. The reason for this is
that the manufacturer has used the panel timings to get a standard EGA mode
to work on flat panel, and these same timings don't work for an SVGA mode.
For these machines the "UseModeline" and/or possibly the "FixPanelSize"
option might be needed. Some machines that are known to need these options
include.

          Modeline "640x480@8bpp"    25.175  640  672  728  816   480  489  501  526
          Modeline "640x480@16bpp"  25.175  640  672  728  816   480  489  501  526
          Options: "UseModeline"
          Tested on a Prostar 8200, (640x480, 65548, 1Mbyte)

          Modeline "800x600@8bpp"    28.322  800  808  848  936   600  600  604  628
          Options: "FixPanelSize", "UseModeline"
          Tested on a HP OmniBook 5000CTS (800x600 TFT, 65548, 1Mbyte)

          Modeline "800x600@8bpp"    30.150  800  896  960 1056   600  600  604  628
          Options: "FixPanelSize", "UseModeline"
          Test on a Zeos Meridan 850c (800x600 DSTN, 65545, 1Mbyte)

The NEC Versa 4080 just needs the "FixPanelSize" option. To the best of my
knowledge no machine with a HiQV needs the "UseModeline" or "FixPanelSize"
options.

5.  The Full Story on Clock Limitations

There has been much confusion about exactly what the clock limitations of the
Chips and Technologies chipsets are. Hence I hope that this section will
clear up the misunderstandings.

In general there are two factors determining the maximum dotclock.  There is
the limit of the maximum dotclock the video processor can handle, and there
is another limitation of the available memory bandwidth. The memory bandwidth
is determined by the clock used for the video memory.  For chipsets incapable
of colour depths greater that 8bpp like the 65535, the dotclock limit is
solely determined by the highest dotclock the video processor is capable of
handling. So this limit will be either 56MHz or 68MHz for the 655xx chipsets,
depending on what voltage they are driven with, or 80MHz for the 64200
WinGine machines.

The 6554x and 64300 WinGine chipsets are capable of colour depths of 16 or
24bpp. However there is no reliable way of probing the memory clock used in
these chipsets, and so a conservative limit must be taken for the dotclock
limit. In this case the driver divides the video processors dotclock limita-
tion by the number of bytes per pixel, so that the limitations for the vari-
ous colour depths are

                             8bpp    16bpp   24bpp
     64300                   85      42.5    28.33
     65540/65545 3.3v        56      28      18.67
     65540/65545 5v          68      34      22.67
     65546/65548             80      40      26.67

For a CRT or TFT screen these limitations are conservative and the user might
safely override them with the "DacSpeed" option to some extent. However these
numbers take no account of the extra bandwidth needed for DSTN screens.

For the HiQV series of chips, the memory clock can be successfully probed.
Hence you will see a line like

     (--) CHIPS(0): Probed memory clock of  40.090 MHz

in your startx log file. Note that many chips are capable of higher memory
clocks than actually set by BIOS. You can use the "SetMClk" option in your
XF86Config file to get a higher MClk. However some video ram, particularly
EDO, might not be fast enough to handle this, resulting in drawing errors on
the screen. The formula to determine the maximum usable dotclock on the HiQV
series of chips is

     Max dotclock = min(MaxDClk,  0.70  * 4 * MemoryClk / (BytesPerPixel +
                     (isDSTN == TRUE ? 1 : 0)))

which says that there are two limits on the dotclock. One the overall maxi-
mum, and another due to the available memory bandwidth of the chip.  For the
memory bandwidth 4 bytes are transfered every clock cycle (Hence the 4), but
after accounting for the RAS/CAS signaling only about 70% of the bandwidth is
available. The whole thing is divided by the bytes per pixel, plus an extra
byte if you are using a DSTN. The extra byte with DSTN screens is used for
the frame buffering/acceleration in these screens. So for the various Chips
and Technologies chips the maximum specifications are

                         Max DClk MHz      Max Mem Clk MHz
     65550 rev A 3.3v          80                38
     65550 rev A 5v           110                38
     65550 rev B               95                50
     65554                     94.5              55
     65555                    110                55
     68554                    110                55
     69000                    135                83
     69030                    170               100

Note that all of the chips except the 65550 rev A are 3.3v only. Which is the
reason for the drop in the dot clock. Now the maximum memory clock is just
the maximum supported by the video processor, not the maximum supported by
the video memory. So the value actually used for the memory clock might be
significantly less than this maximum value. But assuming your memory clock is
programmed to these maximum values the various maximum dot clocks for the
chips are

                             ------CRT/TFT-------    --------DSTN--------
                             8bpp    16bpp   24bpp   8bpp    16bpp   24bpp
     65550 rev A 3.3v        80      53.2    35.47   53.2    35.47   26.6
     65550 rev A 5v          106.2   53.2    35.47   53.2    35.47   26.6
     65550 rev B             95      70      46.67   70      46.67   35.0
     65554                   94.5    77      51.33   77      51.33   38.5
     65555                   110     77      51.33   77      51.33   38.5
     68554                   110     77      51.33   77      51.33   38.5
     69000                   135    116.2    77.47  116.2    77.47   58.1
     69030                   170    140      93.33  140      93.33   70

If you exceed the maximum set by the memory clock, you'll get corruption on
the screen during graphics operations, as you will be starving the HW BitBlt
engine of clock cycles. If you are driving the video memory too fast (too
high a MemClk) you'll get pixel corruption as the data actually written to
the video memory is corrupted by driving the memory too fast. You can proba-
bly get away with exceeding the Max DClk at 8bpp on TFT's or CRT's by up to
10% or so without problems, it will just generate more heat, since the 8bpp
clocks aren't limited by the available memory bandwidth.

If you find you truly can't achieve the mode you are after with the default
clock limitations, look at the options "DacSpeed" and "SetMClk". Using these
should give you all the capabilities you'll need in the server to get a par-
ticular mode to work. However use caution with these options, because there
is no guarantee that driving the video processor beyond it capabilities won't
cause damage.

6.  Troubleshooting

      The cursor appears as a white box, after switching modes
            There is a known bug in the H/W cursor, that sometimes causes the
            cursor to be redrawn as a white box, when the mode is changed.
            This can be fixed by moving the cursor to a different region,
            switching to the console and back again, or if it is too annoying
            the H/W cursor can be disabled by removing the "HWcursor" option.

      The cursor hot-spot isn't at the same point as the cursor
            With modes on the 6555x machines that are stretched to fill the
            flat panel, the H/W cursor is not correspondingly stretched. This
            is a small and long-standing bug in the current server. You can
            avoid this by either using the "NoStretch" option or removing the
            HWcursor" option.

      The lower part of the screen is corrupted
            Many DSTN screens use the top of video ram to implement a frame
            accelerator. This reduces the amount of video ram available to
            the modes. The server doesn't prevent the user from specifying a
            mode that will use this memory, it prints a warning on the con-
            sole.  The effect of this problem will be that the lower part of
            the screen will reside in the same memory as the frame accelera-
            tor and will therefore be corrupt. Try reducing the amount of
            memory consumed by the mode.

      There is a video signal, but the screen doesn't sync.
            You are using a mode that your screen cannot handle. If it is a
            non-standard mode, maybe you need to tweak the timings a bit. If
            it is a standard mode and frequency that your screen should be
            able to handle, try to find different timings for a similar mode
            and frequency combination. For LCD modes, it is possible that
            your LCD panel requires different panel timings at the text con-
            sole than with a graphics mode. In this case you will need the
            "UseModeline" and perhaps also the "FixPanelSize" options to
            reprogram the LCD panel timings to sensible values.

      `Wavy' screen.
            Horizontal waving or jittering of the whole screen, continuously
            (independent from drawing operations).  You are probably using a
            dot clock that is too high (or too low); it is also possible that
            there is interference with a close MCLK. Try a lower dot clock.
            For CRT's you can also try to tweak the mode timings; try
            increasing the second horizontal value somewhat.

      Crash or hang after start-up (probably with a black screen).
            Try the "NoAccel" or one of the XAA acceleration options dis-
            cussed above. Check that the BIOS settings are OK; in particular,
            disable caching of 0xa0000-0xaffff. Disabling hidden DRAM refresh
            may also help.

      Hang as the first text is appearing on the screen on SVR4 machines.
            This problem has been reported under UnixWare 1.x, but not
            tracked down. It doesn't occur under UnixWare 2.x and only occurs
            on the HiQV series of chips. It might affect some other SVR4
            operating systems as well. The workaround is to turn off the use
            of CPU to screen acceleration with the "XaaNoCPUToScreenCol-
            orExapndFill" option.

      Crash, hang, or trash on the screen after a graphics operation.
            This may be related to a bug in one of the accelerated functions,
            or a problem with the BitBLT engine. Try the "NoAccel" or one of
            the XAA acceleration options discussed above. Also check the BIOS
            settings. It is also possible that with a high dot clock and
            depth on a large screen there is very little bandwidth left for
            using the BitBLT engine. Try reducing the clock.

      Chipset is not detected.
            Try forcing the chipset to a type that is most similar to what
            you have.

      The screen is blank when starting X
            One possible cause of this problem with older linux kernels is
            that the "APM_DISPLAY_BLANK" option didn't work correct. Either
            upgrade your kernel or rebuild it with the "APM_DISPLAY_BLANK"
            option disabled. If the problem remains, or you aren't using
            linux, a CRT/LCD or switch to and from the virtual console will
            often fix it.

      Textmode is not properly restored
            This has been reported on some configurations. Many laptops use
            the programmable clock of the 6554x chips at the console.  It is
            not always possible to find out the setting that is used for this
            clock if BIOS has written the MClk after the VClk. Hence the
            server assumes a 25.175MHz clock at the console. This is correct
            for most modes, but can cause some problems. Usually this is
            fixed by switching between the LCD and CRT. Alternatively the
            user can use the "TextClockFreq" option described above to select
            a different clock for the text console. Another possible cause of
            this problem is if linux kernels are compiled with the "APM_DIS-
            PLAY_BLANK" option.  As mentioned before, try disabling this
            option.

      I can't display 640x480 on my 800x600 LCD
            The problem here is that the flat panel needs timings that are
            related to the panel size, and not the mode size. There is no
            facility in the current Xservers to specify these values, and so
            the server attempts to read the panel size from the chip. If the
            user has used the "UseModeline" or "FixPanelSize" options the
            panel timings are derived from the mode, which can be different
            than the panel size. Try deleting theses options  from XF86Config
            or using an LCD/CRT switch.

      I can't get a 320x240 mode to occupy the whole 640x480 LCD
            There is a bug in the 6554x's H/W cursor for modes that are dou-
            bled vertically. The lower half of the screen is not accessible.
            The servers solution to this problem is not to do doubling verti-
            cally.  Which results in the 320x240 mode only expanded to
            640x360. If this is a problem, a work around is to remove the
            "HWcursor" option. The server will then allow the mode to occupy
            the whole 640x480 LCD.

      After a suspend/resume my screen is messed up
            During a suspend/resume, the BIOS controls what is read and writ-
            ten back to the registers. If the screen is using a mode that
            BIOS doesn't know about, then there is no guarantee that it will
            be resumed correctly. For this reason a mode that is as close to
            VESA like as possible should be selected. It is also possible
            that the VGA palette can be affected by a suspend/resume.  Using
            an 8bpp, the colour will then be displayed incorrectly. This
            shouldn't affect higher depths, and is fixable with a switch to
            the virtual console and back.

      The right hand edge of the mode isn't visible on the LCD
            This is usually due to a problem with the "LcdCenter" option. If
            this option is removed form XF86Config, then the problem might go
            away. Alternatively the manufacturer could have incorrectly pro-
            grammed the panel size in the EGA console mode. The "FixPanel-
            Size" can be used to force the modeline values into the panel
            size registers. Two machines that are known to have this problem
            are the "HP OmniBook 5000" and the "NEC  Versa 4080".

      My TFT screen has a reddish tint in 24bpp mode
            For 6554x chipsets the server assumes that the TFT bus width is
            24bits. If this is not true then the screen will appear to have a
            reddish tint. This can be fixed by using the "18BitBus" option.
            Note that the reverse is also true. If the "18BitBus" is used and
            the TFT bus width is 24bpp, then the screen will appear reddish.
            Note that this option only has an effect on TFT screens.

      SuperProbe won't work with my chipset
            At least one non-PCI bus system with a HiQV chipset has been
            found to require the "-no_bios" option for SuperProbe to cor-
            rectly detect the chipset with the factory default BIOS settings.
            The server itself can correctly detect the chip in the same situ-
            ation.

      My 690xx machine lockups when using the "MMIO" option
            The 690xx MMIO mode has been implemented entirely from the manual
            as I don't have the hardware to test it on. At this point no
            testing has been done and it is entirely possible that the "MMIO
            option will lockup your machine. You have been warned! However if
            you do try this option and are willing to debug it, I'd like to
            hear from you.

      My TrueColor windows are corrupted when using the "Overlay" option
            Chips and Technologies specify that the memory clock used with
            the multimedia engine running should be lower than that used
            without. As use of the HiQV chipsets multimedia engine was sup-
            posed to be for things like zoomed video overlays, its use was
            supposed to be occasional and so most machines have their memory
            clock set to a value that is too high for use with the "Overlay"
            option. So with the "Overlay" option, using the "SetMClk" option
            to reduce the speed of the memory clock is recommended.

      The mpeg video playing with the XVideo extension has corrupted colours
            The XVideo extension has only recently been added to the chips
            driver.  Some YUV to RGB colour have been noted at 15 and 16 bit
            colour depths.  However, 8 and 24 bit colour depths seem to work
            fine.

      I can't start X-windows with 16, 24 or 32bpp
            Firstly, is your machine capable of 16/24/32bpp with the mode
            specified. Many LCD displays are incapable of using a 24bpp mode.
            Also you need at least a 65540 to use 16/24bpp and at least a
            65550 for 32bpp. The amount of memory used by the mode will be
            doubled/tripled/quadrupled. The correct options to start the
            server with these modes are

                        startx -- -depth 16             5-6-5 RGB ('64K color', XGA)
                        startx -- -depth 15             5-5-5 RGB ('Hicolor')
                        startx -- -depth 24             8-8-8 RGB truecolor

            or with the HiQV series of chips you might try

                        startx -- -depth 24 -fbbpp 32   8-8-8 RGB truecolor

            however as XFree86 version 4.0.1 allows 32bpp pixmaps to be used
            with framebuffers operating in 24bpp, this mode of operating will
            cost performance for no gain in functionality.

            Note that the "-bpp" option has been removed and replaced with a
            "-depth" and "-fbbpp" option because of the confusion between the
            depth and number of bits per pixel used to represent to frame-
            buffer and the pixmaps in the screens memory.

A general problem with the server that can manifested in many way such as
drawing errors, wavy screens, etc is related to the programmable clock. Many
potential programmable clock register setting are unstable.  However luckily
there are many different clock register setting that can give the same or
very similar clocks. The clock code can be fooled into giving a different and
perhaps more stable clock by simply changing the clock value slightly. For
example 65.00MHz might be unstable while 65.10MHz is not. So for unexplained
problems not addressed above, please try to alter the clock you are using
slightly, say in steps of 0.05MHz and see if the problem goes away. Alterna-
tively, using the "UseVClk1" option with HiQV chips might also help.

For other screen drawing related problems, try the "NoAccel" or one of the
XAA acceleration options discussed above. A useful trick for all laptop com-
puters is to switch between LCD/CRT (usually with something like Fn-F5), if
the screen is having problems.

If you are having driver-related problems that are not addressed by this doc-
ument, or if you have found bugs in accelerated functions, you can try con-
tacting the XFree86 team (the current driver maintainer can be reached at
<dbateman@club-internet.fr> or <eich@xfree86.org>), or post in the Usenet
newsgroup "comp.windows.x.i386unix".

7.  Disclaimer

XFree86, allows the user to do damage to their hardware with software.
Although the authors of this software have tried to prevent this, they dis-
claim all responsibility for any damage caused by the software. Use caution,
if you think the Xserver is frying your screen, TURN THE COMPUTER OFF!!

8.  Acknowledgement

The authors of this software wish to acknowledge the support supplied by
Chips and Technologies during the development of this software.

9.  Authors

Major Contributors (In no particular order)

   o Nozomi Ytow

   o Egbert Eich

   o David Bateman

   o Xavier Ducoin

Contributors (In no particular order)

   o Ken Raeburn

   o Shigehiro Nomura

   o Marc de Courville

   o Adam Sulmicki

   o Jens Maurer

We also thank the many people on the net who have contributed by reporting
bugs and extensively testing this server.

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$XFree86$