gpu: nvgpu: add railgate check in do_idle()

In gk20a_do_idle(), check gk20a rail status before returning.
If rail is off, then only return success otherwise return
failure

Bug 1376916
Bug 1487804

Change-Id: I6280bf06c686b8baa4d6f49e90f47148411c3e02
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/415281
Reviewed-by: Automatic_Commit_Validation_User
GVS: Gerrit_Virtual_Submit
Reviewed-by: Shridhar Rasal <srasal@nvidia.com>
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 13 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/gk20a.c b/drivers/gpu/nvgpu/gk20a/gk20a.c
index b36beb52..2adf8908 100644
--- a/drivers/gpu/nvgpu/gk20a/gk20a.c
+++ b/drivers/gpu/nvgpu/gk20a/gk20a.c
@@ -1658,9 +1658,20 @@ int gk20a_do_idle(void)
         pm_runtime_put_sync(&pdev->dev);
 
         /* add sufficient delay to allow GPU to rail gate */
-        mdelay(platform->railgate_delay + 100);
+        mdelay(platform->railgate_delay);
 
-        return 0;
+        if (platform->is_railgated(pdev))
+                return 0;
+        else {
+                /* wait for some more time */
+                mdelay(100);
+                if (platform->is_railgated(pdev))
+                        return 0;
+        }
+
+        /* GPU is not rail gated by now, return error */
+        up_write(&g->busy_lock);
+        return -EBUSY;
 
 fail:
         pm_runtime_put_noidle(&pdev->dev);