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/*
* Copyright 2005-2006 Luc Verhaegen.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include "minitru-int.h"
/*
* Generate a CVT standard mode from HDisplay, VDisplay and VRefresh.
*
* These calculations are stolen from the CVT calculation spreadsheet written
* by Graham Loveridge. He seems to be claiming no copyright and there seems to
* be no license attached to this. He apparently just wants to see his name
* mentioned.
*
* This file can be found at http://www.vesa.org/Public/CVT/CVTd6r1.xls
*
* Comments and structure corresponds to the comments and structure of the xls.
* This should ease importing of future changes to the standard (not very
* likely though).
*
* About margins; i'm sure that they are to be the bit between HDisplay and
* HBlankStart, HBlankEnd and HTotal, VDisplay and VBlankStart, VBlankEnd and
* VTotal, where the overscan colour is shown. FB seems to call _all_ blanking
* outside sync "margin" for some reason. Since we prefer seeing proper
* blanking instead of the overscan colour, and since the Crtc* values will
* probably get altered after us, we will disable margins altogether. With
* these calculations, Margins will plainly expand H/VDisplay, and we don't
* want that. -- libv
*
*/
struct mt_mode *
mt_cvt_mode(uint32_t hdisplay, uint32_t vdisplay, float refresh, uint32_t flags)
{
struct mt_mode *mode = mt_mode_alloc();
int interlaced = !!(flags & MT_FLAG_INTERLACED);
int reduced = !!(flags & MT_FLAG_REDUCED);
/* 1) top/bottom margin size (% of height) - default: 1.8 */
#define CVT_MARGIN_PERCENTAGE 1.8
/* 2) character cell horizontal granularity (pixels) - default 8 */
#define CVT_H_GRANULARITY 8
/* 4) Minimum vertical porch (lines) - default 3 */
#define CVT_MIN_V_PORCH 3
/* 4) Minimum number of vertical back porch lines - default 6 */
#define CVT_MIN_V_BPORCH 6
/* Pixel Clock step (kHz) */
#define CVT_CLOCK_STEP 250
uint32_t margins = 0;
float vfieldrate, hperiod;
int hdisplayrnd, hmargin;
int vdisplayrnd, vmargin, vsync;
float interlace; /* please rename this */
/* CVT default is 60.0Hz */
if (!refresh)
refresh = 60.0;
/* 1. Required field rate */
if (interlaced)
vfieldrate = refresh * 2;
else
vfieldrate = refresh;
/* 2. Horizontal pixels */
hdisplayrnd = hdisplay - (hdisplay % CVT_H_GRANULARITY);
/* 3. Determine left and right borders */
if (margins) {
/* right margin is actually exactly the same as left */
hmargin = (((float) hdisplayrnd) * CVT_MARGIN_PERCENTAGE / 100.0);
hmargin -= hmargin % CVT_H_GRANULARITY;
} else
hmargin = 0;
/* 4. Find total active pixels */
mode->hdisplay = hdisplayrnd + 2*hmargin;
/* 5. Find number of lines per field */
if (interlaced)
vdisplayrnd = vdisplay / 2;
else
vdisplayrnd = vdisplay;
/* 6. Find top and bottom margins */
/* nope. */
if (margins)
/* top and bottom margins are equal again. */
vmargin = (((float) vdisplayrnd) * CVT_MARGIN_PERCENTAGE / 100.0);
else
vmargin = 0;
mode->vdisplay = vdisplay + 2*vmargin;
/* 7. Interlace */
if (interlaced)
interlace = 0.5;
else
interlace = 0.0;
/* Determine VSync Width from aspect ratio */
if (!(vdisplay % 3) && ((vdisplay * 4 / 3) == hdisplay))
vsync = 4;
else if (!(vdisplay % 9) && ((vdisplay * 16 / 9) == hdisplay))
vsync = 5;
else if (!(vdisplay % 10) && ((vdisplay * 16 / 10) == hdisplay))
vsync = 6;
else if (!(vdisplay % 4) && ((vdisplay * 5 / 4) == hdisplay))
vsync = 7;
else if (!(vdisplay % 9) && ((vdisplay * 15 / 9) == hdisplay))
vsync = 7;
else /* Custom */
vsync = 10;
if (!reduced) { /* simplified GTF calculation */
/* 4) Minimum time of vertical sync + back porch interval (µs)
* default 550.0 */
#define CVT_MIN_VSYNC_BP 550.0
/* 3) Nominal HSync width (% of line period) - default 8 */
#define CVT_HSYNC_PERCENTAGE 8
float hblankpercentage;
int vsyncandbackporch, vbackporch;
int hblank;
/* 8. Estimated Horizontal period */
hperiod = ((float) (1000000.0 / vfieldrate - CVT_MIN_VSYNC_BP)) /
(vdisplayrnd + 2 * vmargin + CVT_MIN_V_PORCH + interlace);
/* 9. Find number of lines in sync + backporch */
if (((int)(CVT_MIN_VSYNC_BP / hperiod) + 1) < (vsync + CVT_MIN_V_PORCH))
vsyncandbackporch = vsync + CVT_MIN_V_PORCH;
else
vsyncandbackporch = (int)(CVT_MIN_VSYNC_BP / hperiod) + 1;
/* 10. Find number of lines in back porch */
vbackporch = vsyncandbackporch - vsync;
/* 11. Find total number of lines in vertical field */
mode->vtotal = vdisplayrnd + 2 * vmargin + vsyncandbackporch + interlace
+ CVT_MIN_V_PORCH;
/* 5) Definition of Horizontal blanking time limitation */
/* Gradient (%/kHz) - default 600 */
#define CVT_M_FACTOR 600
/* Offset (%) - default 40 */
#define CVT_C_FACTOR 40
/* Blanking time scaling factor - default 128 */
#define CVT_K_FACTOR 128
/* Scaling factor weighting - default 20 */
#define CVT_J_FACTOR 20
#define CVT_M_PRIME CVT_M_FACTOR * CVT_K_FACTOR / 256
#define CVT_C_PRIME (CVT_C_FACTOR - CVT_J_FACTOR) * CVT_K_FACTOR / 256 + \
CVT_J_FACTOR
/* 12. Find ideal blanking duty cycle from formula */
hblankpercentage = CVT_C_PRIME - CVT_M_PRIME * hperiod/1000.0;
/* 13. Blanking time */
if (hblankpercentage < 20)
hblankpercentage = 20;
hblank = mode->hdisplay * hblankpercentage/(100.0 - hblankpercentage);
hblank -= hblank % (2*CVT_H_GRANULARITY);
/* 14. Find total number of pixels in a line. */
mode->htotal = mode->hdisplay + hblank;
/* Fill in HSync values */
mode->hsyncend = mode->hdisplay + hblank / 2;
mode->hsyncstart = mode->hsyncend -
(mode->htotal * CVT_HSYNC_PERCENTAGE) / 100;
mode->hsyncstart += CVT_H_GRANULARITY -
mode->hsyncstart % CVT_H_GRANULARITY;
/* Fill in VSync values */
mode->vsyncstart = mode->vdisplay + CVT_MIN_V_PORCH;
mode->vsyncend = mode->vsyncstart + vsync;
} else { /* Reduced blanking */
/* Minimum vertical blanking interval time (µs) - default 460 */
#define CVT_RB_MIN_VBLANK 460.0
/* Fixed number of clocks for horizontal sync */
#define CVT_RB_H_SYNC 32.0
/* Fixed number of clocks for horizontal blanking */
#define CVT_RB_H_BLANK 160.0
/* Fixed number of lines for vertical front porch - default 3 */
#define CVT_RB_VFPORCH 3
int vbilines;
/* 8. Estimate Horizontal period. */
hperiod = ((float) (1000000.0 / vfieldrate - CVT_RB_MIN_VBLANK)) /
(vdisplayrnd + 2*vmargin);
/* 9. Find number of lines in vertical blanking */
vbilines = ((float) CVT_RB_MIN_VBLANK) / hperiod + 1;
/* 10. Check if vertical blanking is sufficient */
if (vbilines < (CVT_RB_VFPORCH + vsync + CVT_MIN_V_BPORCH))
vbilines = CVT_RB_VFPORCH + vsync + CVT_MIN_V_BPORCH;
/* 11. Find total number of lines in vertical field */
mode->vtotal = vdisplayrnd + 2 * vmargin + interlace + vbilines;
/* 12. Find total number of pixels in a line */
mode->htotal = mode->hdisplay + CVT_RB_H_BLANK;
/* Fill in HSync values */
mode->hsyncend = mode->hdisplay + CVT_RB_H_BLANK / 2;
mode->hsyncstart = mode->hsyncend - CVT_RB_H_SYNC;
/* Fill in VSync values */
mode->vsyncstart = mode->vdisplay + CVT_RB_VFPORCH;
mode->vsyncend = mode->vsyncstart + vsync;
}
/* 15/13. Find pixel clock frequency (kHz for xf86) */
mode->clock = mode->htotal * 1000.0 / hperiod;
mode->clock -= mode->clock % CVT_CLOCK_STEP;
/* 18/16. Find actual vertical frame frequency */
/* ignore - just set the mode flag for interlaced */
if (interlaced)
mode->vtotal *= 2;
if (reduced)
mode->flags |= MT_FLAG_PHSYNC | MT_FLAG_NVSYNC;
else
mode->flags |= MT_FLAG_NHSYNC | MT_FLAG_PVSYNC;
if (interlaced)
mode->flags |= MT_FLAG_INTERLACED;
return mode;
}
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