gpu: nvgpu: Simplify ref-counting on VMs

Simplify ref-counting on VMs: take a ref when a VM is bound to a
channel and drop a ref when a channel is freed.

Previously ref-counts were scattered over the driver. Also the CE
and CDE code would bind channels with custom rolled code. This was
because the gk20a_vm_bind_channel() function took an as_share as
the VM argument (the VM was then inferred from that as_share).
However, it is trivial to abtract that bit out and allow a central
bind channel function that just takes a VM and a channel.

Bug 1846718

Change-Id: I156aab259f6c7a2fa338408c6c4a3a464cd44a0c
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: http://git-master/r/1261886
Reviewed-by: Richard Zhao <rizhao@nvidia.com>
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/gk20a/mm_gk20a.h b/drivers/gpu/nvgpu/gk20a/mm_gk20a.h
index 665aea42..f3dffa46 100644
--- a/drivers/gpu/nvgpu/gk20a/mm_gk20a.h
+++ b/drivers/gpu/nvgpu/gk20a/mm_gk20a.h
@@ -707,6 +707,7 @@ int gk20a_vm_free_space(struct gk20a_as_share *as_share,
                         struct nvgpu_as_free_space_args *args);
 int gk20a_vm_bind_channel(struct gk20a_as_share *as_share,
                           struct channel_gk20a *ch);
+int __gk20a_vm_bind_channel(struct vm_gk20a *vm, struct channel_gk20a *ch);
 
 /* batching eliminates redundant cache flushes and invalidates */
 void gk20a_vm_mapping_batch_start(struct vm_gk20a_mapping_batch *batch);