drm/panthor: Revisit reqs_lock handling in flush/reset paths

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panthor_gpu_flush_caches() and panthor_gpu_soft_reset() acquire their
reqs_lock spinlock with the IRQ-disabling variants of the spinlocking
functions. This isn't necessary, as the lock is never taken from an
atomic context, as Panthor uses threaded interrupt handlers. The result
of this overly strict locking is that IRQs may be disabled more
frequently and for longer than they should be, resulting in increased
system latency.

Switch the locking to use non-IRQ-disabling scoped_guard statements for
locking. The wait_event_timeout read of pending_reqs outside of the
spinlock is fine as wait_event_timeout is a memory barrier according to
the Linux Memory Model.

Fixes: 5cd894e258 ("drm/panthor: Add the GPU logical block")
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@collabora.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
Link: https://patch.msgid.link/20260812-panthor-cache-flush-fix-v4-2-751e32901898@collabora.com

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Nicolas Frattaroli 2026-08-12 16:07:19 +02:00 • committed by Liviu Dudau

parent 3fc4721629

commit 4fd08b3d1d

1 changed files with 33 additions and 39 deletions

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drivers/gpu/drm/panthor/panthor_gpu.c

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