Am 14.07.20 um 10:09 schrieb Xiaojie Yuan:
"u64 *wptr" points to the the wptr value in write back buffer and
"*wptr = (*wptr) >> 2;" results in the value being overwritten each time
when ->get_wptr() is called.
umr uses /sys/kernel/debug/dri/0/amdgpu_ring_sdma0 to get rptr/wptr and
decode ring content and it is affected by this issue.
fix and simplify the logic similar as sdma_v4_0_ring_get_wptr().
Suggested-by: Le Ma <le.ma@xxxxxxx>
Signed-off-by: Xiaojie Yuan <xiaojie.yuan@xxxxxxx>
Nice, catch. I'm wondering how this code ever came to be.
Patch is Reviewed-by: Christian König <christian.koenig@xxxxxxx>
Can you please double check that we don't have that nonsense in
sdma_v4_0 or even older as well?
Thanks,
Christian.
---
drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c | 26 ++++++++------------------
1 file changed, 8 insertions(+), 18 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c b/drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c
index abb0ab653b10..e2232dd12d8e 100644
--- a/drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/sdma_v5_0.c
@@ -315,30 +315,20 @@ static uint64_t sdma_v5_0_ring_get_rptr(struct amdgpu_ring *ring)
static uint64_t sdma_v5_0_ring_get_wptr(struct amdgpu_ring *ring)
{
struct amdgpu_device *adev = ring->adev;
- u64 *wptr = NULL;
- uint64_t local_wptr = 0;
+ u64 wptr;
if (ring->use_doorbell) {
/* XXX check if swapping is necessary on BE */
- wptr = ((u64 *)&adev->wb.wb[ring->wptr_offs]);
- DRM_DEBUG("wptr/doorbell before shift == 0x%016llx\n", *wptr);
- *wptr = (*wptr) >> 2;
- DRM_DEBUG("wptr/doorbell after shift == 0x%016llx\n", *wptr);
+ wptr = READ_ONCE(*((u64 *)&adev->wb.wb[ring->wptr_offs]));
+ DRM_DEBUG("wptr/doorbell before shift == 0x%016llx\n", wptr);
} else {
- u32 lowbit, highbit;
-
- wptr = &local_wptr;
- lowbit = RREG32(sdma_v5_0_get_reg_offset(adev, ring->me, mmSDMA0_GFX_RB_WPTR)) >> 2;
- highbit = RREG32(sdma_v5_0_get_reg_offset(adev, ring->me, mmSDMA0_GFX_RB_WPTR_HI)) >> 2;
-
- DRM_DEBUG("wptr [%i]high== 0x%08x low==0x%08x\n",
- ring->me, highbit, lowbit);
- *wptr = highbit;
- *wptr = (*wptr) << 32;
- *wptr |= lowbit;
+ wptr = RREG32(sdma_v5_0_get_reg_offset(adev, ring->me, mmSDMA0_GFX_RB_WPTR_HI));
+ wptr = wptr << 32;
+ wptr |= RREG32(sdma_v5_0_get_reg_offset(adev, ring->me, mmSDMA0_GFX_RB_WPTR));
+ DRM_DEBUG("wptr before shift [%i] wptr == 0x%016llx\n", ring->me, wptr);
}
- return *wptr;
+ return wptr >> 2;
}
/**
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