drm/radeon: only enable swiotlb path when need v2

swiotlb expands our card accessing range, but its path always is slower
than ttm pool allocation.
So add condition to use it.
v2: move a bit later

Signed-off-by: Chunming Zhou <david1.zhou@amd.com>
Reviewed-by: Monk Liu <monk.liu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180209024410.1469-3-david1.zhou@amd.com

3 files changed, 6 insertions, 3 deletions

diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index d34887873dea..4a2eb409aacc 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -2387,6 +2387,7 @@ struct radeon_device {
         struct radeon_dummy_page        dummy_page;
         bool                            shutdown;
         bool                            need_dma32;
+        bool                            need_swiotlb;
         bool                            accel_working;
         bool                            fastfb_working; /* IGP feature*/
         bool                            needs_reset, in_reset;
diff --git a/drivers/gpu/drm/radeon/radeon_device.c b/drivers/gpu/drm/radeon/radeon_device.c
index 8d3e3d2e0090..7f40c6f7c4dd 100644
--- a/drivers/gpu/drm/radeon/radeon_device.c
+++ b/drivers/gpu/drm/radeon/radeon_device.c
@@ -29,6 +29,7 @@
 #include <linux/slab.h>
 #include <drm/drmP.h>
 #include <drm/drm_crtc_helper.h>
+#include <drm/drm_cache.h>
 #include <drm/radeon_drm.h>
 #include <linux/pm_runtime.h>
 #include <linux/vgaarb.h>
@@ -1378,6 +1379,7 @@ int radeon_device_init(struct radeon_device *rdev,
                 pci_set_consistent_dma_mask(rdev->pdev, DMA_BIT_MASK(32));
                 pr_warn("radeon: No coherent DMA available\n");
         }
+        rdev->need_swiotlb = drm_get_max_iomem() > ((u64)1 << dma_bits);
 
         /* Registers mapping */
         /* TODO: block userspace mapping of io register */
diff --git a/drivers/gpu/drm/radeon/radeon_ttm.c b/drivers/gpu/drm/radeon/radeon_ttm.c
index a0a839bc39bf..c1e3862a48a4 100644
--- a/drivers/gpu/drm/radeon/radeon_ttm.c
+++ b/drivers/gpu/drm/radeon/radeon_ttm.c
@@ -756,7 +756,7 @@ static int radeon_ttm_tt_populate(struct ttm_tt *ttm,
 #endif
 
 #ifdef CONFIG_SWIOTLB
-        if (swiotlb_nr_tbl()) {
+        if (rdev->need_swiotlb && swiotlb_nr_tbl()) {
                 return ttm_dma_populate(&gtt->ttm, rdev->dev, ctx);
         }
 #endif
@@ -788,7 +788,7 @@ static void radeon_ttm_tt_unpopulate(struct ttm_tt *ttm)
 #endif
 
 #ifdef CONFIG_SWIOTLB
-        if (swiotlb_nr_tbl()) {
+        if (rdev->need_swiotlb && swiotlb_nr_tbl()) {
                 ttm_dma_unpopulate(&gtt->ttm, rdev->dev);
                 return;
         }
@@ -1155,7 +1155,7 @@ static int radeon_ttm_debugfs_init(struct radeon_device *rdev)
         count = ARRAY_SIZE(radeon_ttm_debugfs_list);
 
 #ifdef CONFIG_SWIOTLB
-        if (!swiotlb_nr_tbl())
+        if (!(rdev->need_swiotlb && swiotlb_nr_tbl()))
                 --count;
 #endif