Debian 8.3 very slow video


#1

I just downloaded and installed the Debian image (on DragonBoard 410C with HDMI 1920x1080), which reports that it’s Debian 8.3.

The board boots up, and various software works more-or-less as expected, except that certain video operations are very slow. In particular, when dragging a window around the screen, the window repaint is many cycles and multiple seconds behind the cursor. Indeed, it might take 10 seconds for a window to come to rest after releasing the mouse.

Command ‘top’ shows process Xorg going close to 100% (of one) CPU during these episodes. Similar behavior for resizing a window, except that in that case the application in question may max out additional CPUs. Chromium for example tries to max out an additional three CPUs.

Anyhow, does this suggest that some aspect of GPU acceleration is not working? Are there settings that need to be enabled? Or is this a known issue?

I did not previously have Debian installed, so I don’t have experience with a previous version to compare.

Graham


#2

So, a couple things… afaiu firefox can use the gst hw video decode and gpu/opengl rendering. The same may not be true for chromium or other apps.

I believe recent db410c releases do have instructions to switch to xf86-video-modesetting (instead of xf86-video-freedreno). The -modesetting DDX with glamor gpu acceleration should support Xv which will help rendering for some apps which support Xv for rendering video but not opengl rendering. So depending on the app, that may help (or at least avoid sw color conversion and scaling).

Also, as a side note, there was recently fixed an issue w/ gpu/bus clock not set correctly which resulted in lower gpu performance. I believe the fix should be in the most recent release. (The relevant kernel commit is https://git.linaro.org/landing-teams/working/qualcomm/kernel.git/patch/01c59c198eb787e00dbdf233257411eb21d24d68 )

(disclaimer, I not actually using the debian release, but just building kernel directly myself)