gpu: nvgpu: take power refcount in ISR

We sometimes see race conditions where power refcount
is zero during ISR or bottom half.
If bottom half calls gk20a_busy(), it will lead to
boot up of GPU, but it is also possible that we are
already trying to poweroff GPU since power refcount
is zero

Fix this by taking a power refcount with gk20a_busy_noresume()
in ISR and then dropping this refcount at the end of
bottom half
Add new API gk20a_idle_nosuspend() to drop a refcount
without initiating suspend

Bug 200198908
Bug 1770522

Change-Id: Iec3d4dc8d468f49b71919d2bbc327da48b97bcab
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/1160035
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Tested-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/gk20a.h b/drivers/gpu/nvgpu/gk20a/gk20a.h
index b7f3f6f1..c7d12f86 100644
--- a/drivers/gpu/nvgpu/gk20a/gk20a.h
+++ b/drivers/gpu/nvgpu/gk20a/gk20a.h
@@ -1060,6 +1060,7 @@ void gk20a_remove_sysfs(struct device *dev);
 
 void gk20a_busy_noresume(struct device *dev);
 int __must_check gk20a_busy(struct device *dev);
+void gk20a_idle_nosuspend(struct device *dev);
 void gk20a_idle(struct device *dev);
 void gk20a_disable(struct gk20a *g, u32 units);
 void gk20a_enable(struct gk20a *g, u32 units);