[PATCH 0/3] Rework panthor's cache flush and soft reset locking
From: Nicolas Frattaroli
Date: Wed Jul 29 2026 - 02:30:19 EST
There are two problems in panthor's cache flushing/soft reset code
related to locking.
The first problem is that the spinlocks are taken with _irqsave, even
though the contended lock is never acquired in a raw interrupt handler.
Only a threaded handler locks it.
The second problem is that the wait_event condition references
pending_reqs without holding the required lock. This means there's a
data race.
While resolving the first problem is easy, the second problem requires
adding some more macro variants to wait.h, which is done in the first
patch.
New tracepoints to debug cache flushing duration without initial locking
waits is thrown in for good measure as well, to complement what's in
lock_stat and what the function tracer can already do.
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@xxxxxxxxxxxxx>
---
Nicolas Frattaroli (3):
wait: Introduce non-irq variants of wait_event_lock_timeout
drm/panthor: Revisit reqs_lock handling in flush/reset paths
drm/panthor: Add tracepoints for cache flushing
drivers/gpu/drm/panthor/panthor_gpu.c | 28 +++++------
drivers/gpu/drm/panthor/panthor_trace.h | 58 +++++++++++++++++++++++
include/linux/wait.h | 84 +++++++++++++++++++++++++++++++++
3 files changed, 156 insertions(+), 14 deletions(-)
---
base-commit: f57436380d5de1c1ded898e21378b0b4159c8790
change-id: 20260728-panthor-cache-flush-fix-b36cb15f92c3
Best regards,
--
Nicolas Frattaroli <nicolas.frattaroli@xxxxxxxxxxxxx>