[ Upstream commit ce050f307ad93bcc5958d0dd35fc276fd394d274 ]
On A5XX GPUs when preemption is used it's invietable to enter a soft
lock-up state in which GPU is stuck at empty ring-buffer doing nothing.
This appears as full UI lockup and not detected as GPU hang (because
it's not). This happens due to not triggering preemption when it was
needed. Sometimes this state can be recovered by some new submit but
generally it won't happen because applications are waiting for old
submits to retire.
One of the reasons why this happens is a race between a5xx_submit and
a5xx_preempt_trigger called from IRQ during submit retire. Former thread
updates ring->cur of previously empty and not current ring right after
latter checks it for emptiness. Then both threads can just exit because
for first one preempt_state wasn't NONE yet and for second one all rings
appeared to be empty.
To prevent such situations from happening we need to establish guarantee
for preempt_trigger to make decision after each submit or retire. To
implement this we serialize preemption initiation using spinlock. If
switch is already in progress we need to re-trigger preemption when it
finishes.
Fixes: b1fc2839d2f9 ("drm/msm: Implement preemption for A5XX targets")
Signed-off-by: Vladimir Lypak <vladimir.lypak@gmail.com>
Patchwork: https://patchwork.freedesktop.org/patch/612045/
Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 64fd6d01a52904bdbda0ce810a45a428c995a4ca ]
Two fields of preempt_record which are used by CP aren't reset on
resume: "data" and "info". This is the reason behind faults which happen
when we try to switch to the ring that was active last before suspend.
In addition those faults can't be recovered from because we use suspend
and resume to do so (keeping values of those fields again).
Fixes: b1fc2839d2f9 ("drm/msm: Implement preemption for A5XX targets")
Signed-off-by: Vladimir Lypak <vladimir.lypak@gmail.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Patchwork: https://patchwork.freedesktop.org/patch/612043/
Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
