linux-kernel - [PATCH 1/2] drm/todo: Add section with task for GPU scheduler

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Message-ID: <20251031120014.248416-3-phasta@kernel.org>
Date: Fri, 31 Oct 2025 13:00:14 +0100
From: Philipp Stanner <phasta@...nel.org>
To: David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	Jonathan Corbet <corbet@....net>
Cc: dri-devel@...ts.freedesktop.org,
	linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Philipp Stanner <phasta@...nel.org>
Subject: [PATCH 1/2] drm/todo: Add section with task for GPU scheduler

The GPU scheduler has a great many problems and deserves its own TODO
section.

Add a section and a first task describing the problem of
drm_sched_resubmit_jobs() being deprecated without a successor.

Signed-off-by: Philipp Stanner <phasta@...nel.org>
---
 Documentation/gpu/todo.rst | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/Documentation/gpu/todo.rst b/Documentation/gpu/todo.rst
index 9013ced318cb..835e799ddfe2 100644
--- a/Documentation/gpu/todo.rst
+++ b/Documentation/gpu/todo.rst
@@ -878,6 +878,37 @@ Contact: Christian König
 
 Level: Starter
 
+DRM GPU Scheduler
+=================
+
+Provide a universal successor for drm_sched_resubmit_jobs()
+------------------------------------------------------------
+
+drm_sched_resubmit_jobs() is deprecated. Main reason being that it leads to
+reinitializing dma_fences. See that function's docu for details. The better
+approach for valid resubmissions by amdgpu and Xe is (apparently) to figure out
+which job (and, through association: which entity) caused the hang. Then, the
+job's buffer data, together with all other jobs' buffer data currently in the
+same hardware ring, must be invalidated. This can for example be done by
+overwriting it. amdgpu currently determines which jobs are in the ring and need
+to be overwritten by keeping copies of the job. Xe obtains that information by
+directly accessing drm_sched's pending_list.
+
+Tasks:
+
+1. implement scheduler functionality through which the driver can obtain the
+   information which *broken* jobs are currently in the hardware ring.
+2. Such infrastructure would then typically be used in
+   drm_sched_backend_ops.timedout_job(). Document that.
+3. Port a driver as first user.
+3. Document the new alternative in the docu of deprecated
+   drm_sched_resubmit_jobs().
+
+Contact: Christian König <ckoenig.leichtzumerken@...il.com>
+         Philipp Stanner <phasta@...nel.org>
+
+Level: Advanced
+
 Outside DRM
 ===========
 
-- 
2.49.0