[Intel-gfx] FBC underruns on GMA4500?

Jesse Barnes jbarnes at virtuousgeek.org
Mon Aug 9 18:36:07 CEST 2010

On Sat, 07 Aug 2010 11:46:19 +0200
Alexey Fisher <bug-track at fisher-privat.net> wrote:

> Hallo all,
> i have some times on my primer desktop with Intel DG45ID board some sort
> of flickering, it schort (1 second) and only half of the display. Same
> sort of flickering i had with Bug 24314 - [945GME FBC] underruns
> followed by freeze after resume with FBC enabled. The difference is - it
> will not freeze.
> If i understand it correctly , it is not normal. But i can't report it,
> there is no messages in dmesg or xorg.log

Sounds like potential FIFO underruns, maybe your memory configuration
doesn't match the latency we expect in intel_display.c.  You could try
increasing the latency constant in that file to see if it makes the
flicker go away.

If that helps it's just another example of why we need better latency
detection in the driver; unfortunately we don't know how to do that

Jesse Barnes, Intel Open Source Technology Center

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