gpu: nvgpu: fix patch buf count update for vidmem

gr_gk20a_ctx_patch_write_begin() updates the patch buffer data_count
when the associated graphics context memory buffer has been
CPU-mapped; it was doing so by looking for a non-null cpu_va.

However, if the graphics context has been allocated from vidmem,
cpu_va is always 0, so we can't tell if nvgpu_mem_begin() was called
for the context buffer or not.

Instead:
- add a cpu_accessible flag to the nvgpu_mem struct and set
  it in nvgpu_mem_begin()

- return the value of that flag in nvgpu_mem_cpu_accessible()

- gr_gk20a_ctx_patch_write_begin() now calls this new function
  instead of checking cpu_va.

Bug 2012077
JIRA ESRM-74

Change-Id: I8401699f30b4ae7154111721c25c7ec3ff95d329
Signed-off-by: Peter Daifuku <pdaifuku@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1587293
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/include/nvgpu/nvgpu_mem.h b/drivers/gpu/nvgpu/include/nvgpu/nvgpu_mem.h
index 6feacff7..bae50347 100644
--- a/drivers/gpu/nvgpu/include/nvgpu/nvgpu_mem.h
+++ b/drivers/gpu/nvgpu/include/nvgpu/nvgpu_mem.h
@@ -122,6 +122,7 @@ struct nvgpu_mem {
         size_t                                   aligned_size;
         u64                                      gpu_va;
         bool                                     skip_wmb;
+        bool                                     cpu_accessible;
 
         /*
          * Set when a nvgpu_mem struct is not a "real" nvgpu_mem struct. Instead
@@ -211,6 +212,15 @@ static inline bool nvgpu_mem_is_valid(struct nvgpu_mem *mem)
 }
 
 /*
+ * Returns true if the passed nvgpu_mem can be accessed by the CPU by virtue
+ * of having called nvgpu_mem_begin successfully.
+ */
+static inline bool nvgpu_mem_cpu_accessible(struct nvgpu_mem *mem)
+{
+        return mem->cpu_accessible;
+}
+
+/*
  * Create a nvgpu_sgt of the default implementation
  */
 struct nvgpu_sgt *nvgpu_sgt_create(struct gk20a *g);