[PATCH 0/1][SRU][N] FPS of glxgear with fullscreen is too low on MTL platform

[AceLan Kao]

From: "Chia-Lin Kao (AceLan)" <acelan.kao at canonical.com>

BugLink: https://bugs.launchpad.net/bugs/2069380

[Impact]
Run `glxgears -fullscreen` and the FPS can't stay at 60 FPS
298 frames in 5.0 seconds = 59.465 FPS
241 frames in 5.0 seconds = 48.193 FPS
261 frames in 5.0 seconds = 52.030 FPS
268 frames in 5.0 seconds = 53.596 FPS

[Fix]
Bisect the kernel and found a commit in v6.9-rc1 fixes the issue
c08c364102d0 drm/i915: Bypass LMEMBAR/GTTMMADR for MTL stolen memory access

[Test]
1. Run `glxgears -fullscreen` on MTL platforms
2. The FPS should be always around 60

[Where problems could occur]
It's a workaround only affects MTL platforms, and there is no
"fixed commit" for this patch after v6.9-rc1. So, it should be safe and
essential for MTL platforms.

Ville Syrjälä (1):
  drm/i915: Bypass LMEMBAR/GTTMMADR for MTL stolen memory access

 drivers/gpu/drm/i915/gem/i915_gem_stolen.c |  6 +++++-
 drivers/gpu/drm/i915/gt/intel_ggtt.c       | 10 +++++++++-
 drivers/gpu/drm/i915/i915_reg.h            |  3 +++
 drivers/gpu/drm/i915/i915_utils.c          | 17 +++++++++++++++++
 drivers/gpu/drm/i915/i915_utils.h          |  2 ++
 5 files changed, 36 insertions(+), 2 deletions(-)

-- 
2.43.0