diff options
| -rw-r--r-- | hw/display/ati.c | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/hw/display/ati.c b/hw/display/ati.c index 6cdcbef238..eb54f6842f 100644 --- a/hw/display/ati.c +++ b/hw/display/ati.c @@ -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); } } |