gpu: nvgpu: hold power ref for deterministic channels

To support deterministic channels even with platforms where railgating
is supported, have each deterministic-marked channel hold a power
reference during their lifetime, and skip taking power refs for jobs in
submit path for those.

Previously, railgating blocked deterministic submits in general because
of gk20a_busy()/gk20a_idle() calls in submit path possibly taking time
and more significantly because the gpu may need turning on which takes a
nondeterministic and long amount of time.

As an exception, gk20a_do_idle() can still block deterministic submits
until gk20a_do_unidle() is called. Add a rwsem to guard this. VPR resize
needs do_idle, which conflicts with deterministic channels' requirement
to keep the GPU on. This is documented in the ioctl header now.

Make NVGPU_GPU_FLAGS_SUPPORT_DETERMINISTIC_SUBMIT_NO_JOBTRACKING always
set in the gpu characteristics now that it's supported. The only thing
left now blocking NVGPU_GPU_FLAGS_SUPPORT_DETERMINISTIC_SUBMIT_FULL is
the sync framework.

Make the channel debug dump show which channels are deterministic.

Bug 200291300
Jira NVGPU-70

Change-Id: I47b6f3a8517cd6e4255f6ca2855e3dd912e4f5f3
Signed-off-by: Konsta Holtta <kholtta@nvidia.com>
Reviewed-on: http://git-master/r/1483038
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/gpu/nvgpu/common/linux/module.c

@@ -298,6 +298,12 @@ int __gk20a_do_idle(struct device *dev, bool force_reset)
 	bool is_railgated;
 	int err = 0;
 
+	/*
+	 * Hold back deterministic submits and changes to deterministic
+	 * channels - this must be outside the power busy locks.
+	 */
+	gk20a_channel_deterministic_idle(g);
+
 	/* acquire busy lock to block other busy() calls */
 	down_write(&g->busy_lock);
 
@@ -403,6 +409,7 @@ fail_drop_usage_count:
 fail_timeout:
 	nvgpu_mutex_release(&platform->railgate_lock);
 	up_write(&g->busy_lock);
+	gk20a_channel_deterministic_unidle(g);
 	return -EBUSY;
 }
 
@@ -456,6 +463,8 @@ int __gk20a_do_unidle(struct device *dev)
 	nvgpu_mutex_release(&platform->railgate_lock);
 	up_write(&g->busy_lock);
 
+	gk20a_channel_deterministic_unidle(g);
+
 	return 0;
 }