gpu: nvgpu: Cleanup usage of bypass_smmu

The GPU has multiple different operating modes in respect to IOMMU'ability.
As such there needs to be a clean way to tell the driver whether it is
IOMMU'able or not. This state also does not always reflect what is possible:
all becasue the GPU can generate IOMMU'ed memory requests doesn't mean it
wants to.

The nvgpu_iommuable() API has now existed for a little while which is a
useful way to convey whether nvgpu should consider the GPU as IOMMU'able.
However, there is also the g->mm.bypass_smmu flag which used to be able to
override what the GPU decided it should do. Typically it was assigned
the same value as nvgpu_iommuable() but that was not necessarily a
requirment.

This patch removes all the usages of g->mm.bypass_smmu and instead uses the
nvgpu_iommuable() function. All places where the check against
g->mm.bypass_smmu have been replaced with nvgpu_iommuable(). The code
should now be much cleaner.

Subsequently other checks can also be placed in the nvgpu_iommuable()
function. For example, when NVLINK comes online and the GPU should no
longer consider DMA addresses and instead use scatter-gather lists
directly the ngpu_iommuable() function will be able to check the state of
NVLINK and then act accordingly.

Change-Id: I0da6262386de15709decac89d63d3eecfec20cd7
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1648332
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

2 files changed, 2 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/common/mm/gmmu.c b/drivers/gpu/nvgpu/common/mm/gmmu.c
index 53ec3029..78ec361e 100644
--- a/drivers/gpu/nvgpu/common/mm/gmmu.c
+++ b/drivers/gpu/nvgpu/common/mm/gmmu.c
@@ -501,7 +501,7 @@ static int __nvgpu_gmmu_do_update_page_table(struct vm_gk20a *vm,
          * mapping is simple since the "physical" address is actually a virtual
          * IO address and will be contiguous.
          */
-        if (attrs->aperture == APERTURE_SYSMEM && !g->mm.bypass_smmu) {
+        if (attrs->aperture == APERTURE_SYSMEM && nvgpu_iommuable(g)) {
                 u64 io_addr = nvgpu_sgt_get_gpu_addr(g, sgt, sgt->sgl, attrs);
 
                 io_addr += space_to_skip;
diff --git a/drivers/gpu/nvgpu/common/mm/nvgpu_mem.c b/drivers/gpu/nvgpu/common/mm/nvgpu_mem.c
index f472d2a0..73b6b2a7 100644
--- a/drivers/gpu/nvgpu/common/mm/nvgpu_mem.c
+++ b/drivers/gpu/nvgpu/common/mm/nvgpu_mem.c
@@ -96,7 +96,7 @@ u64 nvgpu_sgt_alignment(struct gk20a *g, struct nvgpu_sgt *sgt)
          * and double check length of buffer later. Also, since there's an
          * IOMMU we know that this DMA address is contiguous.
          */
-        if (!g->mm.bypass_smmu &&
+        if (nvgpu_iommuable(g) &&
             nvgpu_sgt_iommuable(g, sgt) &&
             nvgpu_sgt_get_dma(sgt, sgt->sgl))
                 return 1ULL << __ffs(nvgpu_sgt_get_dma(sgt, sgt->sgl));