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/* $XFree86: xc/programs/Xserver/hw/xfree86/drivers/ati/atiwonderio.c,v 1.4 2003/01/01 19:16:35 tsi Exp $ */
/*
* Copyright 2000 through 2003 by Marc Aurele La France (TSI @ UQV), tsi@xfree86.org
*
* Permission to use, copy, modify, distribute, and sell this software and its
* documentation for any purpose is hereby granted without fee, provided that
* the above copyright notice appear in all copies and that both that copyright
* notice and this permission notice appear in supporting documentation, and
* that the name of Marc Aurele La France not be used in advertising or
* publicity pertaining to distribution of the software without specific,
* written prior permission. Marc Aurele La France makes no representations
* about the suitability of this software for any purpose. It is provided
* "as-is" without express or implied warranty.
*
* MARC AURELE LA FRANCE DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO
* EVENT SHALL MARC AURELE LA FRANCE BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
* DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
* TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
#include "ati.h"
#include "atichip.h"
#include "atiwonderio.h"
#ifndef AVOID_CPIO
/*
* ATIModifyExtReg --
*
* This function is called to modify certain bits in an ATI extended VGA
* register while preserving its other bits. The function will not write the
* register if it turns out its value would not change. This helps prevent
* server hangs on older adapters.
*/
void
ATIModifyExtReg
(
ATIPtr pATI,
const CARD8 Index,
int CurrentValue,
const CARD8 CurrentMask,
CARD8 NewValue
)
{
/* Possibly retrieve the current value */
if (CurrentValue < 0)
CurrentValue = ATIGetExtReg(Index);
/* Compute new value */
NewValue &= (CARD8)(~CurrentMask);
NewValue |= CurrentValue & CurrentMask;
/* Check if value will be changed */
if (CurrentValue == NewValue)
return;
/*
* The following is taken from ATI's VGA Wonder programmer's reference
* manual which says that this is needed to "ensure the proper state of the
* 8/16 bit ROM toggle". I suspect a timing glitch appeared in the 18800
* after its die was cast. 18800-1 and later chips do not exhibit this
* problem.
*/
if ((pATI->Chip <= ATI_CHIP_18800) && (Index == 0xB2U) &&
((NewValue ^ 0x40U) & CurrentValue & 0x40U))
{
CARD8 misc = inb(R_GENMO);
CARD8 bb = ATIGetExtReg(0xBBU);
outb(GENMO, (misc & 0xF3U) | 0x04U | ((bb & 0x10U) >> 1));
CurrentValue &= (CARD8)(~0x40U);
ATIPutExtReg(0xB2U, CurrentValue);
ATIDelay(5);
outb(GENMO, misc);
ATIDelay(5);
if (CurrentValue != NewValue)
ATIPutExtReg(0xB2U, NewValue);
}
else
ATIPutExtReg(Index, NewValue);
}
#endif /* AVOID_CPIO */
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