drm/panthor: Report innocent group kill

Groups can be killed during a reset even though they did nothing wrong.
That usually happens when the FW is put in a bad state by other groups,
resulting in group suspension failures when the reset happens.

If we end up in that situation, flag the group innocent and report
innocence through a new DRM_PANTHOR_GROUP_STATE flag.

Bump the minor driver version to reflect the uAPI change.

Changes in v4:
- Add an entry to the driver version changelog
- Add R-bs

Changes in v3:
- Actually report innocence to userspace

Changes in v2:
- New patch

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241211080500.2349505-1-boris.brezillon@collabora.com

drivers/gpu/drm/panthor/panthor_drv.c

@@ -1451,6 +1451,7 @@ static const struct file_operations panthor_drm_driver_fops = {
  * - 1.1 - adds DEV_QUERY_TIMESTAMP_INFO query
  * - 1.2 - adds DEV_QUERY_GROUP_PRIORITIES_INFO query
  *       - adds PANTHOR_GROUP_PRIORITY_REALTIME priority
+ * - 1.3 - adds DRM_PANTHOR_GROUP_STATE_INNOCENT flag
  */
 static const struct drm_driver panthor_drm_driver = {
 	.driver_features = DRIVER_RENDER | DRIVER_GEM | DRIVER_SYNCOBJ |
@@ -1464,7 +1465,7 @@ static const struct drm_driver panthor_drm_driver = {
 	.desc = "Panthor DRM driver",
 	.date = "20230801",
 	.major = 1,
-	.minor = 2,
+	.minor = 3,
 
 	.gem_create_object = panthor_gem_create_object,
 	.gem_prime_import_sg_table = drm_gem_shmem_prime_import_sg_table,

drivers/gpu/drm/panthor/panthor_sched.c

@@ -610,6 +610,16 @@ struct panthor_group {
 	 */
 	bool timedout;
 
+	/**
+	 * @innocent: True when the group becomes unusable because the group suspension
+	 * failed during a reset.
+	 *
+	 * Sometimes the FW was put in a bad state by other groups, causing the group
+	 * suspension happening in the reset path to fail. In that case, we consider the
+	 * group innocent.
+	 */
+	bool innocent;
+
 	/**
 	 * @syncobjs: Pool of per-queue synchronization objects.
 	 *
@@ -2676,6 +2686,12 @@ void panthor_sched_suspend(struct panthor_device *ptdev)
 			u32 csg_id = ffs(slot_mask) - 1;
 			struct panthor_csg_slot *csg_slot = &sched->csg_slots[csg_id];
 
+			/* If the group was still usable before that point, we consider
+			 * it innocent.
+			 */
+			if (group_can_run(csg_slot->group))
+				csg_slot->group->innocent = true;
+
 			/* We consider group suspension failures as fatal and flag the
 			 * group as unusable by setting timedout=true.
 			 */
@@ -3517,6 +3533,8 @@ int panthor_group_get_state(struct panthor_file *pfile,
 		get_state->state |= DRM_PANTHOR_GROUP_STATE_FATAL_FAULT;
 		get_state->fatal_queues = group->fatal_queues;
 	}
+	if (group->innocent)
+		get_state->state |= DRM_PANTHOR_GROUP_STATE_INNOCENT;
 	mutex_unlock(&sched->lock);
 
 	group_put(group);

include/uapi/drm/panthor_drm.h

@@ -918,6 +918,15 @@ enum drm_panthor_group_state_flags {
 	 * When a group ends up with this flag set, no jobs can be submitted to its queues.
 	 */
 	DRM_PANTHOR_GROUP_STATE_FATAL_FAULT = 1 << 1,
+
+	/**
+	 * @DRM_PANTHOR_GROUP_STATE_INNOCENT: Group was killed during a reset caused by other
+	 * groups.
+	 *
+	 * This flag can only be set if DRM_PANTHOR_GROUP_STATE_TIMEDOUT is set and
+	 * DRM_PANTHOR_GROUP_STATE_FATAL_FAULT is not.
+	 */
+	DRM_PANTHOR_GROUP_STATE_INNOCENT = 1 << 2,
 };
 
 /**