Fix GPU triggering random system read after VRAM start change

[Jerome Glisse]

On Tue, Jul 31, 2012 at 10:56 AM, Alex Deucher <alexdeucher at gmail.com> wrote:
> On Fri, Jul 27, 2012 at 4:32 PM,  <j.glisse at gmail.com> wrote:
>> So first patch is a fix in itself, smallest possible and should go to
>> stable. Second patch is an improvement as a first step to flicker free
>> boot.
>
> First patch looks ok.  In mc_stop we should disable the crtc and then
> poll CRTC_CONTROL.CRTC_CURRENT_MASTER_EN_STATE until it goes to 0 to
> make sure the crtc has actually stopped reading before we change the
> mc config.  Other than that,

In all my test is was instantaneous, ie less than 1us to take effect,
so i did not wanted to make the patch bigger than it is. But if you
really think we should do that i can readd that code in patch 1.

Cheers,
Jerome

>
> Reviewed-by: Alex Deucher <alexander.deucher at amd.com>
>
>>
>> I have yet extensively tested second patch, especialy not on AGP but
>> so far on few GPU/motherboard it looks good. It can probably wait 3.7.
>> Will test it more and report.
>
> Looks good as well.  A nice clean up to boot.
>
>>
>> I have a third patch that is a step closer to flicker free boot on uefi,
>> waiting ack to release a reg.
>>
>> Cheers,
>> Jerome
>>
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