On 2020-02-05 10:22 a.m., Christian König wrote:
Make use of the better performance here as well.
This patch is only compile tested!
Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 38 +++++++++++++++----------
1 file changed, 23 insertions(+), 15 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index 58d143b24ba0..538c3b52b712 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -1565,7 +1565,7 @@ static int amdgpu_ttm_access_memory(struct ttm_buffer_object *bo,
while (len && pos < adev->gmc.mc_vram_size) {
uint64_t aligned_pos = pos & ~(uint64_t)3;
- uint32_t bytes = 4 - (pos & 3);
+ uint64_t bytes = 4 - (pos & 3);
uint32_t shift = (pos & 3) * 8;
uint32_t mask = 0xffffffff << shift;
@@ -1574,20 +1574,28 @@ static int amdgpu_ttm_access_memory(struct ttm_buffer_object *bo,
bytes = len;
}
- spin_lock_irqsave(&adev->mmio_idx_lock, flags);
- WREG32_NO_KIQ(mmMM_INDEX, ((uint32_t)aligned_pos) | 0x80000000);
- WREG32_NO_KIQ(mmMM_INDEX_HI, aligned_pos >> 31);
- if (!write || mask != 0xffffffff)
- value = RREG32_NO_KIQ(mmMM_DATA);
- if (write) {
- value &= ~mask;
- value |= (*(uint32_t *)buf << shift) & mask;
- WREG32_NO_KIQ(mmMM_DATA, value);
- }
- spin_unlock_irqrestore(&adev->mmio_idx_lock, flags);
- if (!write) {
- value = (value & mask) >> shift;
- memcpy(buf, &value, bytes);
+ if (mask != 0xffffffff) {
+ spin_lock_irqsave(&adev->mmio_idx_lock, flags);
+ WREG32_NO_KIQ(mmMM_INDEX, ((uint32_t)aligned_pos) | 0x80000000);
+ WREG32_NO_KIQ(mmMM_INDEX_HI, aligned_pos >> 31);
+ if (!write || mask != 0xffffffff)
+ value = RREG32_NO_KIQ(mmMM_DATA);
+ if (write) {
+ value &= ~mask;
+ value |= (*(uint32_t *)buf << shift) & mask;
+ WREG32_NO_KIQ(mmMM_DATA, value);
+ }
+ spin_unlock_irqrestore(&adev->mmio_idx_lock, flags);
+ if (!write) {
+ value = (value & mask) >> shift;
+ memcpy(buf, &value, bytes);
+ }
+ } else {
+ bytes = (nodes->start + nodes->size) << PAGE_SHIFT;
+ bytes = min(pos - bytes, (uint64_t)len & ~0x3ull);
I think this is incorrect. The following should be true: pos <
((nodes->start + nodes->size) << PAGE_SHIFT). Consequently pos - bytes
is always negative here. But because you're doing unsigned math it will
underflow to a big positive number, which is never the minimum.
Therefore the min will always be len & ~0x3ull.
I believe this should be min(bytes - pos, (uint64_t)len & ~0x3ull).
Jon, to catch this bug, you'd need a test that first fragments VRAM
(allocates lots of 2MB buffers and frees every other buffer), then
allocates a large non-contiguous buffer. Then you need one 4KB or
smaller access that crosses a boundary between 2MB VRAM buffer chunks.
Christian, your optimized VRAM allocator that tries to get large
contiguous chunks is nice for performance, but it probably has a
tendency to hide this kind of bug. I wonder if we should have a debug
mode that forces non-contiguous buffers to be actually non-contiguous.
Regards,
Felix
+
+ amdgpu_device_vram_access(adev, pos, (uint32_t *)buf,
+ bytes, write);
}
ret += bytes;
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