drm/amdgpu: Correct sdma_v4 get_wptr(v2)

the original method will change the wptr value in wb.
v2:
furthur cleanup

Signed-off-by: Emily Deng <Emily.Deng@amd.com>
Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 7 insertions, 11 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c b/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c
index 3d5385dda34c..87c01d958703 100644
--- a/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c
@@ -238,31 +238,27 @@ static uint64_t sdma_v4_0_ring_get_rptr(struct amdgpu_ring *ring)
 static uint64_t sdma_v4_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;
                 int me = (ring == &adev->sdma.instance[0].ring) ? 0 : 1;
 
-                wptr = &local_wptr;
                 lowbit = RREG32(sdma_v4_0_get_reg_offset(adev, me, mmSDMA0_GFX_RB_WPTR)) >> 2;
                 highbit = RREG32(sdma_v4_0_get_reg_offset(adev, me, mmSDMA0_GFX_RB_WPTR_HI)) >> 2;
 
                 DRM_DEBUG("wptr [%i]high== 0x%08x low==0x%08x\n",
                                 me, highbit, lowbit);
-                *wptr = highbit;
-                *wptr = (*wptr) << 32;
-                *wptr |= lowbit;
+                wptr = highbit;
+                wptr = wptr << 32;
+                wptr |= lowbit;
         }
 
-        return *wptr;
+        return wptr >> 2;
 }
 
 /**