gpu: nvgpu: enable fast submit path

Submit job-tracking is necessary for any of the following
conditions:
- pre- or post-fence functionality
- channel wdt
- GPU rail-gating
- buffer refcounting

If none of the conditions are met, then job tracking is not
required and a fast submit can be done (ie. only need to
write out userspace GPFIFO entries and update GP_PUT).

Bug 1795076

Change-Id: If94d195e3a18a6b623e167829d291ec98a7a43a1
Signed-off-by: Aingara Paramakuru <aparamakuru@nvidia.com>
Reviewed-on: http://git-master/r/1203511
(cherry picked from commit 13d7cfe94559dc52cb0bba7f9e48848e0858be81)
Reviewed-on: http://git-master/r/1223066
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 43 insertions, 19 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
index c8f8c6ce..7df794bf 100644
--- a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
@@ -2201,8 +2201,10 @@ int gk20a_submit_channel_gpfifo(struct channel_gk20a *c,
         bool skip_buffer_refcounting = (flags &
                         NVGPU_SUBMIT_GPFIFO_FLAGS_SKIP_BUFFER_REFCOUNTING);
         int err = 0;
+        bool need_job_tracking;
         struct nvgpu_gpfifo __user *user_gpfifo = args ?
                 (struct nvgpu_gpfifo __user *)(uintptr_t)args->gpfifo : NULL;
+        struct gk20a_platform *platform = gk20a_get_platform(d);
 
         if (c->has_timedout)
                 return -ETIMEDOUT;
@@ -2240,11 +2242,30 @@ int gk20a_submit_channel_gpfifo(struct channel_gk20a *c,
 
         gk20a_dbg_info("channel %d", c->hw_chid);
 
-        /* gk20a_channel_update releases this ref. */
-        err = gk20a_busy(g->dev);
-        if (err) {
-                gk20a_err(d, "failed to host gk20a to submit gpfifo");
-                return err;
+        /*
+         * Job tracking is necessary for any of the following conditions:
+         *  - pre- or post-fence functionality
+         *  - channel wdt
+         *  - GPU rail-gating
+         *  - buffer refcounting
+         *
+         * If none of the conditions are met, then job tracking is not
+         * required and a fast submit can be done (ie. only need to write
+         * out userspace GPFIFO entries and update GP_PUT).
+         */
+        need_job_tracking = (flags & NVGPU_SUBMIT_GPFIFO_FLAGS_FENCE_WAIT) ||
+                        (flags & NVGPU_SUBMIT_GPFIFO_FLAGS_FENCE_GET) ||
+                        c->wdt_enabled ||
+                        platform->can_railgate ||
+                        !skip_buffer_refcounting;
+
+        if (need_job_tracking) {
+                /* gk20a_channel_update releases this ref. */
+                err = gk20a_busy(g->dev);
+                if (err) {
+                        gk20a_err(d, "failed to host gk20a to submit gpfifo");
+                        return err;
+                }
         }
 
         trace_gk20a_channel_submit_gpfifo(dev_name(c->g->dev),
@@ -2274,12 +2295,13 @@ int gk20a_submit_channel_gpfifo(struct channel_gk20a *c,
                 goto clean_up;
         }
 
-
-        err = gk20a_submit_prepare_syncs(c, fence, &wait_cmd, &incr_cmd,
-                                         &pre_fence, &post_fence,
-                                         force_need_sync_fence, flags);
-        if (err)
-                goto clean_up;
+        if (need_job_tracking) {
+                err = gk20a_submit_prepare_syncs(c, fence, &wait_cmd, &incr_cmd,
+                                                 &pre_fence, &post_fence,
+                                                 force_need_sync_fence, flags);
+                if (err)
+                        goto clean_up;
+        }
 
         if (wait_cmd)
                 gk20a_submit_append_priv_cmdbuf(c, wait_cmd);
@@ -2306,8 +2328,9 @@ int gk20a_submit_channel_gpfifo(struct channel_gk20a *c,
                 *fence_out = gk20a_fence_get(post_fence);
         mutex_unlock(&c->last_submit.fence_lock);
 
-        /* TODO! Check for errors... */
-        gk20a_channel_add_job(c, pre_fence, post_fence,
+        if (need_job_tracking)
+                /* TODO! Check for errors... */
+                gk20a_channel_add_job(c, pre_fence, post_fence,
                                 wait_cmd, incr_cmd,
                                 skip_buffer_refcounting);
 
@@ -2317,11 +2340,11 @@ int gk20a_submit_channel_gpfifo(struct channel_gk20a *c,
                 c->gpfifo.put);
 
         trace_gk20a_channel_submitted_gpfifo(dev_name(c->g->dev),
-                                             c->hw_chid,
-                                             num_entries,
-                                             flags,
-                                             post_fence->syncpt_id,
-                                             post_fence->syncpt_value);
+                                c->hw_chid,
+                                num_entries,
+                                flags,
+                                post_fence ? post_fence->syncpt_id : 0,
+                                post_fence ? post_fence->syncpt_value : 0);
 
         gk20a_dbg_info("post-submit put %d, get %d, size %d",
                 c->gpfifo.put, c->gpfifo.get, c->gpfifo.entry_num);
@@ -2335,7 +2358,8 @@ clean_up:
         free_priv_cmdbuf(c, incr_cmd);
         gk20a_fence_put(pre_fence);
         gk20a_fence_put(post_fence);
-        gk20a_idle(g->dev);
+        if (need_job_tracking)
+                gk20a_idle(g->dev);
         return err;
 }