drm/amdgpu: change wptr to 64 bits (v2)

Newer asics need 64 bit wptrs.  If the wptr is now
smaller than the rptr that doesn't indicate a wrap-around
anymore.

v2: integrate Christian's comments.

Signed-off-by: Ken Wang <Qingqing.Wang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index d5eed6b..93ecf69 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -1601,7 +1601,7 @@ static inline void amdgpu_ring_write(struct amdgpu_ring *ring, uint32_t v)
 {
 	if (ring->count_dw <= 0)
 		DRM_ERROR("amdgpu: writing more dwords to the ring than expected!\n");
-	ring->ring[ring->wptr++] = v;
+	ring->ring[ring->wptr++ & ring->buf_mask] = v;
 	ring->wptr &= ring->ptr_mask;
 	ring->count_dw--;
 }