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>

12 files changed, 18 insertions, 25 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)
diff --git a/drivers/gpu/nvgpu/common/linux/debug.c b/drivers/gpu/nvgpu/common/linux/debug.c
index 76018f8d..af3b9964 100644
--- a/drivers/gpu/nvgpu/common/linux/debug.c
+++ b/drivers/gpu/nvgpu/common/linux/debug.c
@@ -332,11 +332,6 @@ void gk20a_debug_init(struct gk20a *g, const char *debugfs_symlink)
                                         l->debugfs,
                                         &g->timeouts_enabled);
 
-        l->debugfs_bypass_smmu =
-                        debugfs_create_bool("bypass_smmu",
-                                        S_IRUGO,
-                                        l->debugfs,
-                                        &g->mm.bypass_smmu);
         l->debugfs_disable_bigpage =
                         debugfs_create_file("disable_bigpage",
                                         S_IRUGO|S_IWUSR,
diff --git a/drivers/gpu/nvgpu/common/linux/dma.c b/drivers/gpu/nvgpu/common/linux/dma.c
index 786065dd..ec9c3b5a 100644
--- a/drivers/gpu/nvgpu/common/linux/dma.c
+++ b/drivers/gpu/nvgpu/common/linux/dma.c
@@ -637,8 +637,13 @@ bool nvgpu_iommuable(struct gk20a *g)
 #ifdef CONFIG_TEGRA_GK20A
         struct nvgpu_os_linux *l = nvgpu_os_linux_from_gk20a(g);
 
-        return device_is_iommuable(l->dev);
-#else
-        return true;
+        /*
+         * Check against the nvgpu device to see if it's been marked as
+         * IOMMU'able.
+         */
+        if (!device_is_iommuable(l->dev))
+                return false;
 #endif
+
+        return true;
 }
diff --git a/drivers/gpu/nvgpu/common/linux/driver_common.c b/drivers/gpu/nvgpu/common/linux/driver_common.c
index ed7f7fe9..9df7ea3f 100644
--- a/drivers/gpu/nvgpu/common/linux/driver_common.c
+++ b/drivers/gpu/nvgpu/common/linux/driver_common.c
@@ -184,7 +184,6 @@ static void nvgpu_init_mm_vars(struct gk20a *g)
 {
         struct gk20a_platform *platform = dev_get_drvdata(dev_from_gk20a(g));
 
-        g->mm.bypass_smmu = platform->bypass_smmu;
         g->mm.disable_bigpage = platform->disable_bigpage;
         __nvgpu_set_enabled(g, NVGPU_MM_HONORS_APERTURE,
                             platform->honors_aperture);
diff --git a/drivers/gpu/nvgpu/common/linux/os_linux.h b/drivers/gpu/nvgpu/common/linux/os_linux.h
index a2181c05..ebe131de 100644
--- a/drivers/gpu/nvgpu/common/linux/os_linux.h
+++ b/drivers/gpu/nvgpu/common/linux/os_linux.h
@@ -123,7 +123,6 @@ struct nvgpu_os_linux {
         struct dentry *debugfs_ltc_enabled;
         struct dentry *debugfs_timeouts_enabled;
         struct dentry *debugfs_gr_idle_timeout_default;
-        struct dentry *debugfs_bypass_smmu;
         struct dentry *debugfs_disable_bigpage;
         struct dentry *debugfs_gr_default_attrib_cb_size;
 
diff --git a/drivers/gpu/nvgpu/common/linux/platform_gk20a.h b/drivers/gpu/nvgpu/common/linux/platform_gk20a.h
index 60e71a74..6994677e 100644
--- a/drivers/gpu/nvgpu/common/linux/platform_gk20a.h
+++ b/drivers/gpu/nvgpu/common/linux/platform_gk20a.h
@@ -106,9 +106,6 @@ struct gk20a_platform {
         /* Timeout for per-channel watchdog (in mS) */
         u32 ch_wdt_timeout_ms;
 
-        /* Enable SMMU bypass by default */
-        bool bypass_smmu;
-
         /* Disable big page support */
         bool disable_bigpage;
 
diff --git a/drivers/gpu/nvgpu/common/linux/platform_gp10b_tegra.c b/drivers/gpu/nvgpu/common/linux/platform_gp10b_tegra.c
index 4dd5d46e..0b0ebeeb 100644
--- a/drivers/gpu/nvgpu/common/linux/platform_gp10b_tegra.c
+++ b/drivers/gpu/nvgpu/common/linux/platform_gp10b_tegra.c
@@ -137,8 +137,7 @@ static int gp10b_tegra_probe(struct device *dev)
                 return ret;
 #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;
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;
diff --git a/drivers/gpu/nvgpu/common/linux/vgpu/gp10b/vgpu_mm_gp10b.c b/drivers/gpu/nvgpu/common/linux/vgpu/gp10b/vgpu_mm_gp10b.c
index 72214d3c..161a69e9 100644
--- a/drivers/gpu/nvgpu/common/linux/vgpu/gp10b/vgpu_mm_gp10b.c
+++ b/drivers/gpu/nvgpu/common/linux/vgpu/gp10b/vgpu_mm_gp10b.c
@@ -23,10 +23,10 @@
 #include "gk20a/mm_gk20a.h"
 
 #include <nvgpu/bug.h>
+#include <nvgpu/dma.h>
 
 int vgpu_gp10b_init_mm_setup_hw(struct gk20a *g)
 {
-        g->mm.bypass_smmu = true;
         g->mm.disable_bigpage = true;
         return 0;
 }
@@ -77,7 +77,7 @@ u64 vgpu_gp10b_locked_gmmu_map(struct vm_gk20a *vm,
 
         /* FIXME: add support for sparse mappings */
 
-        if (WARN_ON(!sgt) || WARN_ON(!g->mm.bypass_smmu))
+        if (WARN_ON(!sgt) || WARN_ON(nvgpu_iommuable(g)))
                 return 0;
 
         if (space_to_skip & (page_size - 1))
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));
diff --git a/drivers/gpu/nvgpu/include/nvgpu/mm.h b/drivers/gpu/nvgpu/include/nvgpu/mm.h
index 90c6946a..4999df2e 100644
--- a/drivers/gpu/nvgpu/include/nvgpu/mm.h
+++ b/drivers/gpu/nvgpu/include/nvgpu/mm.h
@@ -144,7 +144,6 @@ struct mm_gk20a {
         bool use_full_comp_tag_line;
         bool ltc_enabled_current;
         bool ltc_enabled_target;
-        bool bypass_smmu;
         bool disable_bigpage;
         bool has_physical_mode;