drm/amdgpu: use polling mem to set SDMA3 wptr for VF

On Tonga VF, there're 2 sources updating wptr registers for
sdma3: 1) polling mem and 2) doorbell. When doorbell and polling
mem are both enabled on sdma3, there will be collision hit in
occasion between those two sources when ucode and h/w are doing
the updating on wptr register in parallel. Issue doesn't happen
on CP GFX/Compute since CP drops all doorbell writes when VF is
inactive. So enable polling mem and don't use doorbell for SDMA3.

Signed-off-by: Pixel Ding <Pixel.Ding@amd.com>
Reviewed-by: Monk Liu <monk.liu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

2 files changed, 20 insertions, 8 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
index 641e3fd7ba3c..010f69084af5 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ring.h
@@ -186,6 +186,7 @@ struct amdgpu_ring {
         uint64_t                eop_gpu_addr;
         u32                     doorbell_index;
         bool                    use_doorbell;
+        bool                    use_pollmem;
         unsigned                wptr_offs;
         unsigned                fence_offs;
         uint64_t                current_ctx;
diff --git a/drivers/gpu/drm/amd/amdgpu/sdma_v3_0.c b/drivers/gpu/drm/amd/amdgpu/sdma_v3_0.c
index c8c93f9dac21..41c60f5ac96e 100644
--- a/drivers/gpu/drm/amd/amdgpu/sdma_v3_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/sdma_v3_0.c
@@ -355,7 +355,7 @@ static uint64_t sdma_v3_0_ring_get_wptr(struct amdgpu_ring *ring)
         struct amdgpu_device *adev = ring->adev;
         u32 wptr;
 
-        if (ring->use_doorbell) {
+        if (ring->use_doorbell || ring->use_pollmem) {
                 /* XXX check if swapping is necessary on BE */
                 wptr = ring->adev->wb.wb[ring->wptr_offs] >> 2;
         } else {
@@ -380,10 +380,13 @@ static void sdma_v3_0_ring_set_wptr(struct amdgpu_ring *ring)
 
         if (ring->use_doorbell) {
                 u32 *wb = (u32 *)&adev->wb.wb[ring->wptr_offs];
-
                 /* XXX check if swapping is necessary on BE */
                 WRITE_ONCE(*wb, (lower_32_bits(ring->wptr) << 2));
                 WDOORBELL32(ring->doorbell_index, lower_32_bits(ring->wptr) << 2);
+        } else if (ring->use_pollmem) {
+                u32 *wb = (u32 *)&adev->wb.wb[ring->wptr_offs];
+
+                WRITE_ONCE(*wb, (lower_32_bits(ring->wptr) << 2));
         } else {
                 int me = (ring == &ring->adev->sdma.instance[0].ring) ? 0 : 1;
 
@@ -718,10 +721,14 @@ static int sdma_v3_0_gfx_resume(struct amdgpu_device *adev)
                 WREG32(mmSDMA0_GFX_RB_WPTR_POLL_ADDR_HI + sdma_offsets[i],
                        upper_32_bits(wptr_gpu_addr));
                 wptr_poll_cntl = RREG32(mmSDMA0_GFX_RB_WPTR_POLL_CNTL + sdma_offsets[i]);
-                if (amdgpu_sriov_vf(adev))
-                        wptr_poll_cntl = REG_SET_FIELD(wptr_poll_cntl, SDMA0_GFX_RB_WPTR_POLL_CNTL, F32_POLL_ENABLE, 1);
+                if (ring->use_pollmem)
+                        wptr_poll_cntl = REG_SET_FIELD(wptr_poll_cntl,
+                                                       SDMA0_GFX_RB_WPTR_POLL_CNTL,
+                                                       ENABLE, 1);
                 else
-                        wptr_poll_cntl = REG_SET_FIELD(wptr_poll_cntl, SDMA0_GFX_RB_WPTR_POLL_CNTL, F32_POLL_ENABLE, 0);
+                        wptr_poll_cntl = REG_SET_FIELD(wptr_poll_cntl,
+                                                       SDMA0_GFX_RB_WPTR_POLL_CNTL,
+                                                       ENABLE, 0);
                 WREG32(mmSDMA0_GFX_RB_WPTR_POLL_CNTL + sdma_offsets[i], wptr_poll_cntl);
 
                 /* enable DMA RB */
@@ -1203,9 +1210,13 @@ static int sdma_v3_0_sw_init(void *handle)
         for (i = 0; i < adev->sdma.num_instances; i++) {
                 ring = &adev->sdma.instance[i].ring;
                 ring->ring_obj = NULL;
-                ring->use_doorbell = true;
-                ring->doorbell_index = (i == 0) ?
-                        AMDGPU_DOORBELL_sDMA_ENGINE0 : AMDGPU_DOORBELL_sDMA_ENGINE1;
+                if (!amdgpu_sriov_vf(adev)) {
+                        ring->use_doorbell = true;
+                        ring->doorbell_index = (i == 0) ?
+                                AMDGPU_DOORBELL_sDMA_ENGINE0 : AMDGPU_DOORBELL_sDMA_ENGINE1;
+                } else {
+                        ring->use_pollmem = true;
+                }
 
                 sprintf(ring->name, "sdma%d", i);
                 r = amdgpu_ring_init(adev, ring, 1024,