gpu: nvgpu: support suspend/resume with user disabled railgating

We take an extra power refcount when we disable railgating
through railgate_enable sysfs
And that breaks suspend/resume since we check for power
refcount first in gk20a_pm_suspend()

Fix this with following :
- set a flag user_railgate_disabled when User
  disables railgating through sysfs railgate_enable
- in gk20a_pm_suspend(), drop one power refcount
  if flag is set
- in gk20a_pm_resume(), take one refcount again
  if flag is set

Fix __gk20a_do_idle() to consider this extra refcount as well.
Add new variable target_ref_cnt and use it instead of
assuming target refcount of 1

In case User has disabled rail gating, set this target
refcount as 2

Also, export gk20a_idle_nosuspend() which drop power refcount
without triggering suspend

Bug 200233570

Change-Id: Ic0e35c73eb74ffefea1cd90d1b152650d9d2043d
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: http://git-master/r/1236047
(cherry picked from commit 6e002d57da4b5c58ed79889728bb678d3aa1f1b1)
Reviewed-on: http://git-master/r/1235219
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/gk20a_sysfs.c b/drivers/gpu/nvgpu/gk20a/gk20a_sysfs.c
index 875a99ce..a79ec201 100644
--- a/drivers/gpu/nvgpu/gk20a/gk20a_sysfs.c
+++ b/drivers/gpu/nvgpu/gk20a/gk20a_sysfs.c
@@ -294,12 +294,14 @@ static ssize_t railgate_enable_store(struct device *dev,
                 /* release extra ref count */
                 gk20a_idle(dev);
                 platform->can_railgate = true;
+                platform->user_railgate_disabled = false;
         } else if (railgate_enable == 0 && platform->can_railgate) {
                 /* take extra ref count */
                 err = gk20a_busy(dev);
                 if (err)
                         return err;
                 platform->can_railgate = false;
+                platform->user_railgate_disabled = true;
         }
         if (err)
                 return err;