Screen distortion on ThinkPad 240X with SiliconMotion SM712

[Alex Bowden]

Hi all,


I'm getting terrible screen distortion/tearing with a SiliconMotion SM712 LynxEM+ with 4MB of video ram.


If you google around it seems the issue has been seen by others too, but I *think* only with EXA enabled. I have not seen the problem when acceleration is disabled. I dug into the

EXA code in the xf86-video-siliconmotion driver and found that if I modify the EXA "offScreenBase" in SMI_EXAInit() the tearing is drastically reduced. In my testing I just set it to memorySize/2. I do not know what the proper method is. I did try to disable the offscreen memory manager but that caused Xorg to panic somewhere after "Initializing DRI2".


I am looking for any suggestions. I'd like to eventually get a fix checked in if possible.


Thanks,

Alex
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