drm/msm: Docs and misc cleanup

Fix a couple incorrect or misspelt comments, and add submitqueue doc
comment.
Signed-off-by: Rob Clark <robdclark@chromium.org>
Acked-by: Christian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20210728010632.2633470-2-robdclark@gmail.comSigned-off-by: Rob Clark <robdclark@chromium.org>

drivers/gpu/drm/msm/msm_gem.h

@@ -313,8 +313,7 @@ void msm_gem_vunmap(struct drm_gem_object *obj);
 
 /* Created per submit-ioctl, to track bo's and cmdstream bufs, etc,
  * associated with the cmdstream submission for synchronization (and
- * make it easier to unwind when things go wrong, etc).  This only
- * lasts for the duration of the submit-ioctl.
+ * make it easier to unwind when things go wrong, etc).
  */
 struct msm_gem_submit {
 	struct kref ref;

drivers/gpu/drm/msm/msm_gem_submit.c

@@ -655,6 +655,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data,
 	bool has_ww_ticket = false;
 	unsigned i;
 	int ret, submitid;
+
 	if (!gpu)
 		return -ENXIO;
 

drivers/gpu/drm/msm/msm_gpu.h

@@ -250,6 +250,21 @@ struct msm_gpu_perfcntr {
 	const char *name;
 };
 
+/**
+ * A submitqueue is associated with a gl context or vk queue (or equiv)
+ * in userspace.
+ *
+ * @id:        userspace id for the submitqueue, unique within the drm_file
+ * @flags:     userspace flags for the submitqueue, specified at creation
+ *             (currently unusued)
+ * @prio:      the submitqueue priority
+ * @faults:    the number of GPU hangs associated with this submitqueue
+ * @ctx:       the per-drm_file context associated with the submitqueue (ie.
+ *             which set of pgtables do submits jobs associated with the
+ *             submitqueue use)
+ * @node:      node in the context's list of submitqueues
+ * @ref:       reference count
+ */
 struct msm_gpu_submitqueue {
 	int id;
 	u32 flags;

drivers/gpu/drm/msm/msm_ringbuffer.c

@@ -32,7 +32,7 @@ struct msm_ringbuffer *msm_ringbuffer_new(struct msm_gpu *gpu, int id,
 
 	if (IS_ERR(ring->start)) {
 		ret = PTR_ERR(ring->start);
-		ring->start = 0;
+		ring->start = NULL;
 		goto fail;
 	}
 

drivers/gpu/drm/msm/msm_submitqueue.c

@@ -98,17 +98,18 @@ int msm_submitqueue_create(struct drm_device *drm, struct msm_file_private *ctx,
 	return 0;
 }
 
+/*
+ * Create the default submit-queue (id==0), used for backwards compatibility
+ * for userspace that pre-dates the introduction of submitqueues.
+ */
 int msm_submitqueue_init(struct drm_device *drm, struct msm_file_private *ctx)
 {
 	struct msm_drm_private *priv = drm->dev_private;
 	int default_prio;
 
-	if (!ctx)
-		return 0;
-
 	/*
 	 * Select priority 2 as the "default priority" unless nr_rings is less
-	 * than 2 and then pick the lowest pirority
+	 * than 2 and then pick the lowest priority
 	 */
 	default_prio = priv->gpu ?
 		clamp_t(uint32_t, 2, 0, priv->gpu->nr_rings - 1) : 0;