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, 4 insertions, 3 deletions

diff --git a/drivers/gpu/nvgpu/common/linux/cde_gp10b.c b/drivers/gpu/nvgpu/common/linux/cde_gp10b.c
index ffae6e34..483a3ee7 100644
--- a/drivers/gpu/nvgpu/common/linux/cde_gp10b.c
+++ b/drivers/gpu/nvgpu/common/linux/cde_gp10b.c
@@ -26,6 +26,7 @@
 #include "cde_gp10b.h"
 
 #include <nvgpu/log.h>
+#include <nvgpu/dma.h>
 
 enum gp10b_programs {
         GP10B_PROG_HPASS              = 0,
@@ -56,10 +57,10 @@ void gp10b_cde_get_program_numbers(struct gk20a *g,
                         hprog = GP10B_PROG_HPASS_DEBUG;
                         vprog = GP10B_PROG_VPASS_DEBUG;
                 }
-                if (g->mm.bypass_smmu) {
+                if (!nvgpu_iommuable(g)) {
                         if (!g->mm.disable_bigpage) {
                                 nvgpu_warn(g,
-                                           "when bypass_smmu is 1, disable_bigpage must be 1 too");
+                                           "When no IOMMU big pages cannot be used");
                         }
                         hprog |= 1;
                         vprog |= 1;
@@ -72,7 +73,7 @@ void gp10b_cde_get_program_numbers(struct gk20a *g,
 
 bool gp10b_need_scatter_buffer(struct gk20a *g)
 {
-        return g->mm.bypass_smmu;
+        return !nvgpu_iommuable(g);
 }
 
 static u8 parity(u32 a)