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ati-vga: Fix GPIO_MONID register write

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Also update bitbang_i2c state when output bits are changed while
enable bits are set. This fixes EDID access by the ATI FCode ROM.

Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Message-id: 292e70a92b7fbfd9a4120d433dbdcfda4e5f6c3c.1565558093.git.balaton@eik.bme.hu
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
BALATON Zoltan 2019-08-11 23:14:53 +02:00 committed by Gerd Hoffmann
parent df1e4cf4e7
commit 006388a8c7
1 changed files with 7 additions and 4 deletions
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11
hw/display/ati.c
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@ -564,12 +564,15 @@ static void ati_mm_write(void *opaque, hwaddr addr,
addr - GPIO_MONID, data, size);
/*
* Rage128p accesses DDC used to get EDID via these bits.
* Only touch i2c when write overlaps 3rd byte because some
* drivers access this reg via multiple partial writes and
* without this spurious bits would be sent.
* Because some drivers access this via multiple byte writes
* we have to be careful when we send bits to avoid spurious
* changes in bitbang_i2c state. So only do it when mask is set
* and either the enable bits are changed or output bits changed
* while enabled.
*/
if ((s->regs.gpio_monid & BIT(25)) &&
addr <= GPIO_MONID + 2 && addr + size > GPIO_MONID + 2) {
((addr <= GPIO_MONID + 2 && addr + size > GPIO_MONID + 2) ||
(addr == GPIO_MONID && (s->regs.gpio_monid & 0x60000)))) {
s->regs.gpio_monid = ati_i2c(&s->bbi2c, s->regs.gpio_monid, 1);
}
}