Fix GPU triggering random system read after VRAM start change

[Alex Deucher]

On Tue, Jul 31, 2012 at 11:15 AM, Jerome Glisse <j.glisse at gmail.com> wrote:
> 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.

Thinking about it more, It should fine as is since we take the crtc lock.

Alex