[PATCH v16 04/16] accel/rocket: let the core suspend after a reset

[Jiaxing Hu <gahing@gahingwoo.com>]

The reset path drops the runtime PM reference with
pm_runtime_put_noidle(), which does not let the device suspend, so the
power domain is never switched off and on again.

On the RK3576, powering the domain on resets the NPU bus interface. If
that does not happen after a reset, the IOMMU may not respond and the
next job after a timeout fails.

Use pm_runtime_put_autosuspend() instead, so the reset path handles
runtime PM the same way as a normal job completion.

Also drop the runtime PM reference after rocket_core_reset(), so the NPU
core stays powered during the reset.

The earlier test on the ROCK 4D was done on the v15 code: the job after a
timeout went from all 128 channels wrong to all 128 correct.

Repeated resets were triggered with a 2 ms job timeout.

v15 (put, then reset): tested twice; both times the board hung within the
same second as the first batch of job timeouts, with nothing printed.

v16 (reset, then put): tested four times; the board never hung.

So moving pm_runtime_put_autosuspend() after rocket_core_reset() avoids
the board hanging during a reset.

Link: https://lore.kernel.org/all/20260819073530.6087-1-royalnet026@gmail.com/
Fixes: 0810d5ad88a1 ("accel/rocket: Add job submission IOCTL")
Signed-off-by: Jiaxing Hu <gahing@gahingwoo.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
---
 drivers/accel/rocket/rocket_job.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/accel/rocket/rocket_job.c b/drivers/accel/rocket/rocket_job.c
index abef12b86d48..4a577b642849 100644
--- a/drivers/accel/rocket/rocket_job.c
+++ b/drivers/accel/rocket/rocket_job.c
@@ -395,6 +395,8 @@ static void rocket_job_handle_irq(struct rocket_core *core)
 static void
 rocket_reset(struct rocket_core *core, struct drm_sched_job *bad)
 {
+	bool put_job_ref;
+
 	if (!atomic_read(&core->reset.pending))
 		return;
 
@@ -413,11 +415,10 @@ rocket_reset(struct rocket_core *core, struct drm_sched_job *bad)
 	/*
 	 * Remaining interrupts have been handled, but we might still have
 	 * stuck jobs. Let's make sure the PM counters stay balanced by
-	 * manually calling pm_runtime_put_noidle().
+	 * dropping the job's reference once the core has been reset.
 	 */
 	scoped_guard(mutex, &core->job_lock) {
-		if (core->in_flight_job)
-			pm_runtime_put_noidle(core->dev);
+		put_job_ref = core->in_flight_job;
 
 		iommu_detach_group(NULL, core->iommu_group);
 
@@ -427,6 +428,9 @@ rocket_reset(struct rocket_core *core, struct drm_sched_job *bad)
 	/* Proceed with reset now. */
 	rocket_core_reset(core);
 
+	if (put_job_ref)
+		pm_runtime_put_autosuspend(core->dev);
+
 	/* NPU has been reset, we can clear the reset pending bit. */
 	atomic_set(&core->reset.pending, 0);
 
-- 
2.43.0