drm/amdgpu: change gfx9 ib test to use WB

two reasons to switch SCRATCH reg method to WB method:

1)Because when doing IB test we don't want to involve KIQ health
status affect, and since SCRATCH register access is go through
KIQ that way GFX IB test would failed due to KIQ fail.

2)acccessing SCRATCH register cost much more time than WB method
because SCRATCH register access runs through KIQ which at least could
begin after GPU world switch back to current Guest VF
Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gfx_v9_0.c

@@ -274,26 +274,32 @@ static int gfx_v9_0_ring_test_ib(struct amdgpu_ring *ring, long timeout)
 	struct amdgpu_device *adev = ring->adev;
 	struct amdgpu_ib ib;
 	struct dma_fence *f = NULL;
-        uint32_t scratch;
-        uint32_t tmp = 0;
+
+	unsigned index;
+	uint64_t gpu_addr;
+	uint32_t tmp;
 	long r;
 
-        r = amdgpu_gfx_scratch_get(adev, &scratch);
+	r = amdgpu_device_wb_get(adev, &index);
 	if (r) {
-                DRM_ERROR("amdgpu: failed to get scratch reg (%ld).\n", r);
+		dev_err(adev->dev, "(%ld) failed to allocate wb slot\n", r);
 		return r;
 	}
-        WREG32(scratch, 0xCAFEDEAD);
+
+	gpu_addr = adev->wb.gpu_addr + (index * 4);
+	adev->wb.wb[index] = cpu_to_le32(0xCAFEDEAD);
 	memset(&ib, 0, sizeof(ib));
-        r = amdgpu_ib_get(adev, NULL, 256, &ib);
+	r = amdgpu_ib_get(adev, NULL, 16, &ib);
 	if (r) {
 		DRM_ERROR("amdgpu: failed to get ib (%ld).\n", r);
 		goto err1;
 	}
-        ib.ptr[0] = PACKET3(PACKET3_SET_UCONFIG_REG, 1);
-        ib.ptr[1] = ((scratch - PACKET3_SET_UCONFIG_REG_START));
-        ib.ptr[2] = 0xDEADBEEF;
-        ib.length_dw = 3;
+	ib.ptr[0] = PACKET3(PACKET3_WRITE_DATA, 3);
+	ib.ptr[1] = WRITE_DATA_DST_SEL(5) | WR_CONFIRM;
+	ib.ptr[2] = lower_32_bits(gpu_addr);
+	ib.ptr[3] = upper_32_bits(gpu_addr);
+	ib.ptr[4] = 0xDEADBEEF;
+	ib.length_dw = 5;
 
 	r = amdgpu_ib_schedule(ring, 1, &ib, NULL, &f);
 	if (r)
@@ -308,20 +314,21 @@ static int gfx_v9_0_ring_test_ib(struct amdgpu_ring *ring, long timeout)
 			DRM_ERROR("amdgpu: fence wait failed (%ld).\n", r);
 			goto err2;
 	}
-        tmp = RREG32(scratch);
+
+	tmp = adev->wb.wb[index];
 	if (tmp == 0xDEADBEEF) {
 			DRM_DEBUG("ib test on ring %d succeeded\n", ring->idx);
 			r = 0;
 	} else {
-                DRM_ERROR("amdgpu: ib test failed (scratch(0x%04X)=0x%08X)\n",
-                          scratch, tmp);
+			DRM_ERROR("ib test on ring %d failed\n", ring->idx);
 			r = -EINVAL;
 	}
+
 err2:
 	amdgpu_ib_free(adev, &ib, NULL);
 	dma_fence_put(f);
 err1:
-        amdgpu_gfx_scratch_free(adev, scratch);
+	amdgpu_device_wb_free(adev, index);
 	return r;
 }