Commit 87edca62 authored by Philipp Stanner's avatar Philipp Stanner
Browse files

drm/sched: Adjust outdated docu for run_job() 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.

Furthermore, the scheduler expects to "inherit" a reference on the fence
from the run_job() callback. This, so far, is also not documented.

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.

Document the necessity of incrementing the refcount in run_job().

Acked-by: default avatarDanilo Krummrich <dakr@kernel.org>
Signed-off-by: default avatarPhilipp Stanner <phasta@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20250305130551.136682-3-phasta@kernel.org
parent b72f66f2

include/drm/gpu_scheduler.h

+30 −4
Original line number Diff line number Diff line
@@ -411,9 +411,35 @@ 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.

	 *

	 * @sched_job: the job to run

	 *

	 * The deprecated drm_sched_resubmit_jobs() (called by &struct

	 * drm_sched_backend_ops.timedout_job) can invoke this again with the

	 * same parameters. Using this is discouraged because it violates

	 * dma_fence rules, notably dma_fence_init() has to be called on

	 * already initialized fences for a second time. Moreover, this is

	 * dangerous because attempts to allocate memory might deadlock with

	 * memory management code waiting for the reset to complete.

	 *

	 * TODO: Document what drivers should do / use instead.

	 *

	 * This method is called in a workqueue context - either from the

	 * submit_wq the driver passed through drm_sched_init(), or, if the

	 * driver passed NULL, a separate, ordered workqueue the scheduler

	 * allocated.

	 *

	 * Note that the scheduler expects to 'inherit' its own reference to

	 * this fence from the callback. It does not invoke an extra

	 * dma_fence_get() on it. Consequently, this callback must take a

	 * reference for the scheduler, and additional ones for the driver's

	 * respective needs.

	 *

	 * Return:

	 * * On success: dma_fence the driver must signal once the hardware has

	 * completed the job ("hardware fence").

	 * * On failure: NULL or an ERR_PTR.

	 */

	struct dma_fence *(*run_job)(struct drm_sched_job *sched_job);