Bug#682099: xserver-xorg-video-ati: EXAPixmaps=On screen tearing at high resolution under certain configurations

[Alex Deucher]

On Fri, Jul 20, 2012 at 1:45 PM, Michel Dänzer <daenzer at debian.org> wrote:
> On Don, 2012-07-19 at 23:43 +1000, James Robertson wrote:
>> Package: xserver-xorg-video-ati
>> Version: 1:6.14.4-5
>> Severity: normal
>>
>> Dear Maintainer,
>>
>> I have a Lenovo R500 laptop with an "[AMD] nee ATI RV620 [Mobility Radeon HD 3400
>> Series]" graphics chip
>>
>> I recently obtained 2x AOC monitors with a 1920x1080 resolution and have
>> these connected via DVI and VGA to a laptop docking station.
>>
>> The laptop only supports a maximum of 2 displays at once.
>>
>> With the laptop display disabled I get screen tearing and corruption when
>> using 1 or both of the external monitors with 1920x1080 resolution.
>> But strangely if I set one of them to a lower resolution such as 1680x1050
>> (the other still at 1920x1080) the screen tearing issue dissapears.  Odd given
>> a single display gets the tearing...
>>
>> If using the laptop's display in conjunction with either DVI or VGA
>> connected monitor at 1920x1080 I experience no tearing.
>>

Also note that rendering can only be synchronized to one head at a
time to avoid tearing.  If you have windows that span multiple heads,
you may get tearing on the non-synced heads.

Alex