From 4c8ef550cc3b02c7c783364ae8006c3c3d75b244 Mon Sep 17 00:00:00 2001
From: "Xiangliang.Yu" <Xiangliang.Yu@amd.com>
Date: Wed, 13 Sep 2017 10:58:19 +0800
Subject: [PATCH 1832/4131] drm/amdgpu/sdma3: set wptr shadow atomically

Port it from sdma4 for wptr polling usage.

Signed-off-by: Xiangliang.Yu <Xiangliang.Yu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/sdma_v3_0.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/sdma_v3_0.c b/drivers/gpu/drm/amd/amdgpu/sdma_v3_0.c
index 7b97ce8..10a0ceb 100644
--- a/drivers/gpu/drm/amd/amdgpu/sdma_v3_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/sdma_v3_0.c
@@ -379,8 +379,10 @@ static void sdma_v3_0_ring_set_wptr(struct amdgpu_ring *ring)
 	struct amdgpu_device *adev = ring->adev;
 
 	if (ring->use_doorbell) {
+		u32 *wb = (u32 *)&adev->wb.wb[ring->wptr_offs];
+
 		/* XXX check if swapping is necessary on BE */
-		adev->wb.wb[ring->wptr_offs] = lower_32_bits(ring->wptr) << 2;
+		WRITE_ONCE(*wb, (lower_32_bits(ring->wptr) << 2));
 		WDOORBELL32(ring->doorbell_index, lower_32_bits(ring->wptr) << 2);
 	} else {
 		int me = (ring == &ring->adev->sdma.instance[0].ring) ? 0 : 1;
-- 
2.7.4