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>

1 files changed, 1 insertions, 2 deletions

diff --git a/drivers/gpu/nvgpu/common/linux/platform_gv11b_tegra.c b/drivers/gpu/nvgpu/common/linux/platform_gv11b_tegra.c
index c56bc0f3..7d7fc603 100644
--- a/drivers/gpu/nvgpu/common/linux/platform_gv11b_tegra.c
+++ b/drivers/gpu/nvgpu/common/linux/platform_gv11b_tegra.c
@@ -81,8 +81,7 @@ static int gv11b_tegra_probe(struct device *dev)
         g->has_syncpoints = false;
 #endif
 
-        platform->bypass_smmu = !device_is_iommuable(dev);
-        platform->disable_bigpage = platform->bypass_smmu;
+        platform->disable_bigpage = !device_is_iommuable(dev);
 
         platform->g->gr.ctx_vars.dump_ctxsw_stats_on_channel_close
                 = false;