gpu: nvgpu: fix event id polling

In gk20a_event_id_poll(), we always set the mask value
and return it. This causes poll() from UMD to be always
successful irrespective of event is really generated or not

Fix this by adding a flag event_posted for each event
Set this flag while posting the event
In gk20a_event_id_poll(), set the mask value only if
this flag is set. If flag is set, set mask and clear the flag

Bug 200089620

Change-Id: If14236547c611fe4bfa1410ff5b69c9fa02d43bb
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/1160253
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>

3 files changed, 18 insertions, 7 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
index a5243834..02ec5835 100644
--- a/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/channel_gk20a.c
@@ -2519,18 +2519,25 @@ static unsigned int gk20a_event_id_poll(struct file *filep, poll_table *wait)
         if (event_id_data->is_tsg) {
                 struct tsg_gk20a *tsg = g->fifo.tsg + event_id_data->id;
 
-                gk20a_dbg_info(
-                        "found pending event_id=%d on TSG=%d\n",
-                        event_id, tsg->tsgid);
+                if (event_id_data->event_posted) {
+                        gk20a_dbg_info(
+                                "found pending event_id=%d on TSG=%d\n",
+                                event_id, tsg->tsgid);
+                        mask = (POLLPRI | POLLIN);
+                        event_id_data->event_posted = false;
+                }
         } else {
                 struct channel_gk20a *ch = g->fifo.channel
                                            + event_id_data->id;
 
-                gk20a_dbg_info(
-                        "found pending event_id=%d on chid=%d\n",
-                        event_id, ch->hw_chid);
+                if (event_id_data->event_posted) {
+                        gk20a_dbg_info(
+                                "found pending event_id=%d on chid=%d\n",
+                                event_id, ch->hw_chid);
+                        mask = (POLLPRI | POLLIN);
+                        event_id_data->event_posted = false;
+                }
         }
-        mask = (POLLPRI | POLLIN);
 
         mutex_unlock(&event_id_data->lock);
 
@@ -2609,6 +2616,7 @@ void gk20a_channel_event_id_post_event(struct channel_gk20a *ch,
         gk20a_dbg_info(
                 "posting event for event_id=%d on ch=%d\n",
                 event_id, ch->hw_chid);
+        event_id_data->event_posted = true;
 
         wake_up_interruptible_all(&event_id_data->event_id_wq);
 
diff --git a/drivers/gpu/nvgpu/gk20a/channel_gk20a.h b/drivers/gpu/nvgpu/gk20a/channel_gk20a.h
index 29a13d24..4e0db3cf 100644
--- a/drivers/gpu/nvgpu/gk20a/channel_gk20a.h
+++ b/drivers/gpu/nvgpu/gk20a/channel_gk20a.h
@@ -84,6 +84,8 @@ struct gk20a_event_id_data {
         bool is_tsg;
         u32 event_id;
 
+        bool event_posted;
+
         wait_queue_head_t event_id_wq;
         struct mutex lock;
         struct list_head event_id_node;
diff --git a/drivers/gpu/nvgpu/gk20a/tsg_gk20a.c b/drivers/gpu/nvgpu/gk20a/tsg_gk20a.c
index 5298d380..f7d5535d 100644
--- a/drivers/gpu/nvgpu/gk20a/tsg_gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/tsg_gk20a.c
@@ -231,6 +231,7 @@ void gk20a_tsg_event_id_post_event(struct tsg_gk20a *tsg,
         gk20a_dbg_info(
                 "posting event for event_id=%d on tsg=%d\n",
                 event_id, tsg->tsgid);
+        event_id_data->event_posted = true;
 
         wake_up_interruptible_all(&event_id_data->event_id_wq);