drm/amdgpu: assign the doorbell index in 1st page to sdma page queue

Previously for vega10, the sdma_doorbell_range is only enough for sdma
gfx queue, thus the index on second doorbell page is allocated for sdma
page queue. From vega20, the sdma_doorbell_range on 1st page is enlarged.
Therefore, just leverage these index instead of allocation on 2nd page.

v2: change "(x << 1) + 2" to "(x + 1) << 1" for readability and add comments.
Signed-off-by: Le Ma <le.ma@amd.com>
Acked-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1091,7 +1091,8 @@ static int amdgpu_device_doorbell_init(struct amdgpu_device *adev)
 		 * doorbells are in the first page. So with paging queue enabled,
 		 * the max num_kernel_doorbells should + 1 page (0x400 in dword)
 		 */
-		if (adev->asic_type >= CHIP_VEGA10)
+		if (adev->ip_versions[SDMA0_HWIP][0] >= IP_VERSION(4, 0, 0) &&
+		    adev->ip_versions[SDMA0_HWIP][0] < IP_VERSION(4, 2, 0))
 			adev->doorbell.num_kernel_doorbells += 0x400;
 	}
 

drivers/gpu/drm/amd/amdgpu/sdma_v4_0.c

@@ -1847,8 +1847,18 @@ static int sdma_v4_0_sw_init(void *handle)
 			/* paging queue use same doorbell index/routing as gfx queue
 			 * with 0x400 (4096 dwords) offset on second doorbell page
 			 */
-			ring->doorbell_index = adev->doorbell_index.sdma_engine[i] << 1;
-			ring->doorbell_index += 0x400;
+			if (adev->ip_versions[SDMA0_HWIP][0] >= IP_VERSION(4, 0, 0) &&
+			    adev->ip_versions[SDMA0_HWIP][0] < IP_VERSION(4, 2, 0)) {
+				ring->doorbell_index =
+					adev->doorbell_index.sdma_engine[i] << 1;
+				ring->doorbell_index += 0x400;
+			} else {
+				/* From vega20, the sdma_doorbell_range in 1st
+				 * doorbell page is reserved for page queue.
+				 */
+				ring->doorbell_index =
+					(adev->doorbell_index.sdma_engine[i] + 1) << 1;
+			}
 
 			if (adev->ip_versions[SDMA0_HWIP][0] == IP_VERSION(4, 2, 2) && i >= 5)
 				ring->vm_hub = AMDGPU_MMHUB1(0);

drivers/gpu/drm/amd/amdgpu/sdma_v4_4_2.c

@@ -1323,11 +1323,10 @@ static int sdma_v4_4_2_sw_init(void *handle)
 			ring->ring_obj = NULL;
 			ring->use_doorbell = true;
 
-			/* paging queue use same doorbell index/routing as gfx queue
-			 * with 0x400 (4096 dwords) offset on second doorbell page
+			/* doorbell index of page queue is assigned right after
+			 * gfx queue on the same instance
 			 */
-			ring->doorbell_index = adev->doorbell_index.sdma_engine[i] << 1;
-			ring->doorbell_index += 0x400;
+			ring->doorbell_index = (adev->doorbell_index.sdma_engine[i] + 1) << 1;
 			ring->vm_hub = AMDGPU_MMHUB0(0);
 
 			sprintf(ring->name, "page%d", i);