[PATCH 3/4] drm/amdgpu: use amdgpu_device_vram_access in amdgpu_ttm_vram_read

[Christian König]

This speeds up the access quite a bit from 2.2 MB/s to
2.9 MB/s on 32bit and 12,8 MB/s on 64bit.

Signed-off-by: Christian König <christian.koe...@amd.com>
Reviewed-by: Alex Deucher <alexander.deuc...@amd.com>
Acked-by: Jonathan Kim <jonathan....@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 27 ++++++++++---------------
 1 file changed, 11 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index ae1b00def5d8..58d143b24ba0 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -59,6 +59,8 @@
 #include "amdgpu_ras.h"
 #include "bif/bif_4_1_d.h"
 
+#define AMDGPU_TTM_VRAM_MAX_DW_READ    (size_t)128
+
 static int amdgpu_map_buffer(struct ttm_buffer_object *bo,
                             struct ttm_mem_reg *mem, unsigned num_pages,
                             uint64_t offset, unsigned window,
@@ -2255,27 +2257,20 @@ static ssize_t amdgpu_ttm_vram_read(struct file *f, 
char __user *buf,
        if (*pos >= adev->gmc.mc_vram_size)
                return -ENXIO;
 
+       size = min(size, (size_t)(adev->gmc.mc_vram_size - *pos));
        while (size) {
-               unsigned long flags;
-               uint32_t value;
-
-               if (*pos >= adev->gmc.mc_vram_size)
-                       return result;
-
-               spin_lock_irqsave(&adev->mmio_idx_lock, flags);
-               WREG32_NO_KIQ(mmMM_INDEX, ((uint32_t)*pos) | 0x80000000);
-               WREG32_NO_KIQ(mmMM_INDEX_HI, *pos >> 31);
-               value = RREG32_NO_KIQ(mmMM_DATA);
-               spin_unlock_irqrestore(&adev->mmio_idx_lock, flags);
+               size_t bytes = min(size, AMDGPU_TTM_VRAM_MAX_DW_READ * 4);
+               uint32_t value[AMDGPU_TTM_VRAM_MAX_DW_READ];
 
-               r = put_user(value, (uint32_t *)buf);
+               amdgpu_device_vram_access(adev, *pos, value, bytes, false);
+               r = copy_to_user(buf, value, bytes);
                if (r)
                        return r;
 
-               result += 4;
-               buf += 4;
-               *pos += 4;
-               size -= 4;
+               result += bytes;
+               buf += bytes;
+               *pos += bytes;
+               size -= bytes;
        }
 
        return result;
-- 
2.17.1

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