linux-kernel - [PATCH v2 2/3] drm/sched: Adjust outdated docu for run

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Message-ID: <20250121151544.44949-5-phasta@kernel.org>
Date: Tue, 21 Jan 2025 16:15:45 +0100
From: Philipp Stanner <phasta@...nel.org>
To: Matthew Brost <matthew.brost@...el.com>,
	Danilo Krummrich <dakr@...nel.org>,
	Philipp Stanner <pstanner@...hat.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Sumit Semwal <sumit.semwal@...aro.org>,
	Christian König <christian.koenig@....com>
Cc: dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	linux-media@...r.kernel.org,
	linaro-mm-sig@...ts.linaro.org,
	Philipp Stanner <phasta@...nel.org>
Subject: [PATCH v2 2/3] drm/sched: Adjust outdated docu for run_job()

The documentation for drm_sched_backend_ops.run_job() mentions a certain
function called drm_sched_job_recovery(). This function does not exist.
What's actually meant is drm_sched_resubmit_jobs(), which is by now also
deprecated.

Remove the mention of the removed function.

Discourage the behavior of drm_sched_backend_ops.run_job() being called
multiple times for the same job.

Signed-off-by: Philipp Stanner <phasta@...nel.org>
---
Folks, I need input for those "refcount" rules. I say that we either
delete that section or someone (Christian?) should provide details about
what those rules are, as Danilo requested.

P.
---
 include/drm/gpu_scheduler.h | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
index d5cd2a78f27c..cf40fdb55541 100644
--- a/include/drm/gpu_scheduler.h
+++ b/include/drm/gpu_scheduler.h
@@ -421,14 +421,19 @@ struct drm_sched_backend_ops {
 
 	/**
 	 * @run_job: Called to execute the job once all of the dependencies
-	 * have been resolved. This may be called multiple times, if
-	 * timedout_job() has happened and drm_sched_job_recovery() decides to
-	 * try it again.
+	 * have been resolved.
+	 *
+	 * The deprecated drm_sched_resubmit_jobs() (called from
+	 * drm_sched_backend_ops.timedout_job()) can invoke this again with the
+	 * same parameters. Doing this is strongly discouraged because it
+	 * violates dma_fence rules.
 	 *
 	 * @sched_job: the job to run
 	 *
-	 * Returns: dma_fence the driver must signal once the hardware has
-	 *	completed the job ("hardware fence").
+	 * Returns:
+	 * On success: dma_fence the driver must signal once the hardware has
+	 * completed the job ("hardware fence").
+	 * On failure: NULL or an ERR_PTR.
 	 *
 	 * Note that the scheduler expects to 'inherit' its own reference to
 	 * this fence from the callback. It does not invoke an extra
-- 
2.47.1