linux-kernel - [PATCH v2 8/9] drm/msm/A6XX: Add a flag to allow preemption to submitqueue

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Message-Id: <20240830-preemption-a750-t-v2-8-86aeead2cd80@gmail.com>
Date: Fri, 30 Aug 2024 17:32:50 +0200
From: Antonino Maniscalco <antomani103@...il.com>
To: Rob Clark <robdclark@...il.com>, Sean Paul <sean@...rly.run>, 
 Konrad Dybcio <konrad.dybcio@...aro.org>, 
 Abhinav Kumar <quic_abhinavk@...cinc.com>, 
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, 
 Marijn Suijten <marijn.suijten@...ainline.org>, 
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>
Cc: linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
 freedreno@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 Antonino Maniscalco <antomani103@...il.com>, 
 Neil Armstrong <neil.armstrong@...aro.org>
Subject: [PATCH v2 8/9] drm/msm/A6XX: Add a flag to allow preemption to
 submitqueue_create

Some userspace changes are necessary so add a flag for userspace to
advertise support for preemption when creating the submitqueue.

When this flag is not set preemption will not be allowed in the middle
of the submitted IBs therefore mantaining compatibility with older
userspace.

The flag is rejected if preemption is not supported on the target, this
allows userspace to know whether preemption is supported.

Signed-off-by: Antonino Maniscalco <antomani103@...il.com>
Tested-by: Neil Armstrong <neil.armstrong@...aro.org> # on SM8650-QRD
---
 drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 12 ++++++++----
 drivers/gpu/drm/msm/msm_submitqueue.c |  3 +++
 include/uapi/drm/msm_drm.h            |  5 ++++-
 3 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
index 3528ecbbc1ab..a2853309288b 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
@@ -465,8 +465,10 @@ static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 	OUT_PKT7(ring, CP_SET_MARKER, 1);
 	OUT_RING(ring, 0x101); /* IFPC disable */
 
-	OUT_PKT7(ring, CP_SET_MARKER, 1);
-	OUT_RING(ring, 0x00d); /* IB1LIST start */
+	if (submit->queue->flags & MSM_SUBMITQUEUE_ALLOW_PREEMPT) {
+		OUT_PKT7(ring, CP_SET_MARKER, 1);
+		OUT_RING(ring, 0x00d); /* IB1LIST start */
+	}
 
 	/* Submit the commands */
 	for (i = 0; i < submit->nr_cmds; i++) {
@@ -497,8 +499,10 @@ static void a7xx_submit(struct msm_gpu *gpu, struct msm_gem_submit *submit)
 			update_shadow_rptr(gpu, ring);
 	}
 
-	OUT_PKT7(ring, CP_SET_MARKER, 1);
-	OUT_RING(ring, 0x00e); /* IB1LIST end */
+	if (submit->queue->flags & MSM_SUBMITQUEUE_ALLOW_PREEMPT) {
+		OUT_PKT7(ring, CP_SET_MARKER, 1);
+		OUT_RING(ring, 0x00e); /* IB1LIST end */
+	}
 
 	get_stats_counter(ring, REG_A7XX_RBBM_PERFCTR_CP(0),
 		rbmemptr_stats(ring, index, cpcycles_end));
diff --git a/drivers/gpu/drm/msm/msm_submitqueue.c b/drivers/gpu/drm/msm/msm_submitqueue.c
index 4ffb336d9a60..0a8fc4262026 100644
--- a/drivers/gpu/drm/msm/msm_submitqueue.c
+++ b/drivers/gpu/drm/msm/msm_submitqueue.c
@@ -176,6 +176,9 @@ int msm_submitqueue_create(struct drm_device *drm, struct msm_file_private *ctx,
 	if (!priv->gpu)
 		return -ENODEV;
 
+	if (flags & MSM_SUBMITQUEUE_ALLOW_PREEMPT && gpu->nr_rings == 1)
+		return -EINVAL;
+
 	ret = msm_gpu_convert_priority(priv->gpu, prio, &ring_nr, &sched_prio);
 	if (ret)
 		return ret;
diff --git a/include/uapi/drm/msm_drm.h b/include/uapi/drm/msm_drm.h
index 3fca72f73861..f37858db34e6 100644
--- a/include/uapi/drm/msm_drm.h
+++ b/include/uapi/drm/msm_drm.h
@@ -345,7 +345,10 @@ struct drm_msm_gem_madvise {
  * backwards compatibility as a "default" submitqueue
  */
 
-#define MSM_SUBMITQUEUE_FLAGS (0)
+#define MSM_SUBMITQUEUE_ALLOW_PREEMPT	0x00000001
+#define MSM_SUBMITQUEUE_FLAGS		    ( \
+		MSM_SUBMITQUEUE_ALLOW_PREEMPT | \
+		0)
 
 /*
  * The submitqueue priority should be between 0 and MSM_PARAM_PRIORITIES-1,

-- 
2.46.0