Re: Flickering with page-flipping on Acer Iconia W500 (AMD C-50 APU)

[Felix Kuehling <felix.kuehling@amd.com>]

On 12-02-21 07:49 PM, Mario Kleiner wrote:
> On 02/21/2012 09:07 PM, Alex Deucher wrote:
[snip]
>> The fix looks ok to me.  Mario any thoughts?
>>
>> Reviewed-by: Alex Deucher<alexdeucher@gmail.com>
>>
>
> Hi,
>
> the fix looks ok to me for that device, but could we make it
> conditional on the AMD C-50 APU and similar pieces? It is the right
> thing to do for that gpu, but for regular desktop gpus it is too
> pessimistic if it defers the pageflip timestamping and completion
> event for an already completed flip:
>
> 1. Makes the timestamps 1 refresh too late, causing timing sensitive
> software like mine to detect false positives -- reporting skipped
> frames were there weren't any. Not as bad as missing a really skipped
> frame, but still not great.

Agreed. I was going to perform some more experiments on other hardware
to determine what the right threshold is for different hardware
generations. I hope I'll get to that this week.

>
> 2. Can reduce the framerate due to throttling the client, especially
> on systems that are already challenged wrt. to their irq timing.
>
> Is the vblank period very short on these kind of devices? From Felix
> description is sounds as if it is only 2 scanlines?

It looks like that.

Thanks for the feedback,
  Felix

>
> thanks,
> -mario
>

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