Re: [PATCH v1 2/4] drm/xe/mcr: Sanitize steering semaphore on GT resume

[Navon John Lukose <navonjohnlukose@gmail.com>]

On Tue, 21 Jul 2026 21:46:52 -0300, Tales A. Mendonça wrote:
> Port that to xe: release the steering semaphore at the start of
> xe_gt_resume(), before the first MCR access performed by
> do_gt_restart().

Tested on an ARL-H 7d51 (Lenovo Yoga Pro 7 14IAH10). Without this
patch, 7.2.8 hits the drm_WARN_ON_ONCE in mcr_lock() on the first
s2idle resume of every boot, lid open or closed.

With this patch on the same 7.2.8 build, without 1/4, the first
resume no longer warns. Later resumes can't show the _ONCE WARN
anyway, but a debug read of STEER_SEMAPHORE just before the release
found GT1's semaphore held on both resumes of that boot and GT0's
free, so the release is what fixes it. xe_gt_resume() already holds
XE_FORCEWAKE_ALL at that point, so the forcewake in 1/4 isn't needed
for this WARN.

Tested-by: Navon John Lukose <navonjohnlukose@gmail.com>