[PATCH v9 03/13] accel/rocket: let the core suspend after a reset

rocket_reset() drops the in-flight job's runtime PM reference with
pm_runtime_put_noidle(), a bare decrement that requests nothing. The core
is left at usage_count 0 but still runtime-active with no idle request
pending, so it does not suspend until something else asks, and on a
platform whose power domain does work on power-on that work never happens.

On RK3576 that work is a bus interface reset the domain cycles when it
comes up. Without it the NPU's IOMMU stops answering, and the job after a
timeout returns a surface of the output zero point with rk_iommu reporting
that MMU_DTE_ADDR is not functioning.

Measured on a ROCK 4D in one boot, three runs, one variable between them.
With the bare put the core reads runtime-active with its rail still up
after the reset, the IOMMU reports the failure on the next attach and the
inference returns 0 of 128 channels. With the reference put back through
pm_runtime_put_autosuspend() the core reads suspended with the rail down,
there is no IOMMU message, and the same inference returns 128 of 128. A
third run repeating the first failed the same way.

It also matches the put in the completion path a few lines away, so the
reset path no longer leaves the device in a state the rest of the driver
never produces. The remaining put, on the error path in rocket_job_run(),
is a plain pm_runtime_put() and is left alone here: it unwinds a
get_sync() that never reached the hardware, and changing it belongs in
its own patch.

Igor Paunovic ran the differential on RK3588: 45 induced resets across
three cores, with and without the two preceding patches, and the domain
dropped every single time with no MMU message on either kernel. So this
is not rocket-wide. His conditions cross a healthy block with a lowered
timeout rather than a hung one, which he was careful to say his protocol
cannot settle, but it is what scopes the change to RK3576.

Link: https://lore.kernel.org/all/[email protected]/
Fixes: 0810d5ad88a1 ("accel/rocket: Add job submission IOCTL")
Signed-off-by: Jiaxing Hu <[email protected]>
---
 drivers/accel/rocket/rocket_job.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/accel/rocket/rocket_job.c b/drivers/accel/rocket/rocket_job.c
index 3c0ed4605..a89ab49e1 100644
--- a/drivers/accel/rocket/rocket_job.c
+++ b/drivers/accel/rocket/rocket_job.c
@@ -406,12 +406,12 @@ rocket_reset(struct rocket_core *core, struct drm_sched_job *bad)
 
 	/*
 	 * No handler is running now, but we might still have stuck jobs. Let's
-	 * make sure the PM counters stay balanced by manually calling
-	 * pm_runtime_put_noidle().
+	 * make sure the PM counters stay balanced by putting the reference the
+	 * job took, and request idle while doing it so the core can suspend.
 	 */
 	scoped_guard(mutex, &core->job_lock) {
 		if (core->in_flight_job)
-			pm_runtime_put_noidle(core->dev);
+			pm_runtime_put_autosuspend(core->dev);
 
 		iommu_detach_group(NULL, core->iommu_group);
 
-- 
2.43.0