bisected/regression: choopy youtube video on Ryzen IGP - 0ddd2ae586d2 drm/ttm: increase ttm pre-fault value to PMD size

[Yanko Kaneti]

Hello,

Noticed and bisected a rawhide (with the new 6.11-rc0 snapshots) regression to this commit:

  0ddd2ae586d2 drm/ttm: increase ttm pre-fault value to PMD size

The regression manifests in choppy youtube video playback in google-chrome-stable.
 https://www.youtube.com/watch?v=uOpl2XNOgMA
 google-chrome-stable-126.0.6478.182-1.x86_64
 VP9 video, 
 Chrome -> Override software rendering list -> on
 Chrome -> Hardware-accelerated video decode - default enabled

No other visible graphics issues.

Its a desktop system with Ryzen 7 5700GRyzen 7 5700G  IGP
[AMD/ATI] Cezanne [Radeon Vega Series / Radeon Vega Mobile Series] [1002:1638]

Tested with linus tip and just reverting the commit fixes the issue.

Sorry for the brevity, not sure what other details might be relevant.

- Yanko