drm/amdgpu: Use correct VIEWPORT_DIMENSION for DCN2

For some reason this file isn't using the appropriate register
headers for DCN headers, which means that on DCN2 we're getting
the VIEWPORT_DIMENSION offset wrong.

This means that we're not correctly carving out the framebuffer
memory correctly for a framebuffer allocated by EFI and
therefore see corruption when loading amdgpu before the display
driver takes over control of the framebuffer scanout.

Fix this by checking the DCE_HWIP and picking the correct offset
accordingly.

Long-term we should expose this info from DC as GMC shouldn't
need to know about DCN registers.

Cc: stable@vger.kernel.org
Signed-off-by: Harry Wentland <harry.wentland@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c

@@ -72,6 +72,9 @@
 #define mmDCHUBBUB_SDPIF_MMIO_CNTRL_0                                                                  0x049d
 #define mmDCHUBBUB_SDPIF_MMIO_CNTRL_0_BASE_IDX                                                         2
 
+#define mmHUBP0_DCSURF_PRI_VIEWPORT_DIMENSION_DCN2                                                          0x05ea
+#define mmHUBP0_DCSURF_PRI_VIEWPORT_DIMENSION_DCN2_BASE_IDX                                                 2
+
 
 static const char *gfxhub_client_ids[] = {
 	"CB",
@@ -1134,6 +1137,8 @@ static unsigned gmc_v9_0_get_vbios_fb_size(struct amdgpu_device *adev)
 	u32 d1vga_control = RREG32_SOC15(DCE, 0, mmD1VGA_CONTROL);
 	unsigned size;
 
+	/* TODO move to DC so GMC doesn't need to hard-code DCN registers */
+
 	if (REG_GET_FIELD(d1vga_control, D1VGA_CONTROL, D1VGA_MODE_ENABLE)) {
 		size = AMDGPU_VBIOS_VGA_ALLOCATION;
 	} else {
@@ -1142,7 +1147,6 @@ static unsigned gmc_v9_0_get_vbios_fb_size(struct amdgpu_device *adev)
 		switch (adev->ip_versions[DCE_HWIP][0]) {
 		case IP_VERSION(1, 0, 0):
 		case IP_VERSION(1, 0, 1):
-		case IP_VERSION(2, 1, 0):
 			viewport = RREG32_SOC15(DCE, 0, mmHUBP0_DCSURF_PRI_VIEWPORT_DIMENSION);
 			size = (REG_GET_FIELD(viewport,
 					      HUBP0_DCSURF_PRI_VIEWPORT_DIMENSION, PRI_VIEWPORT_HEIGHT) *
@@ -1150,6 +1154,14 @@ static unsigned gmc_v9_0_get_vbios_fb_size(struct amdgpu_device *adev)
 					      HUBP0_DCSURF_PRI_VIEWPORT_DIMENSION, PRI_VIEWPORT_WIDTH) *
 				4);
 			break;
+		case IP_VERSION(2, 1, 0):
+			viewport = RREG32_SOC15(DCE, 0, mmHUBP0_DCSURF_PRI_VIEWPORT_DIMENSION_DCN2);
+			size = (REG_GET_FIELD(viewport,
+					      HUBP0_DCSURF_PRI_VIEWPORT_DIMENSION, PRI_VIEWPORT_HEIGHT) *
+				REG_GET_FIELD(viewport,
+					      HUBP0_DCSURF_PRI_VIEWPORT_DIMENSION, PRI_VIEWPORT_WIDTH) *
+				4);
+			break;
 		default:
 			viewport = RREG32_SOC15(DCE, 0, mmSCL0_VIEWPORT_SIZE);
 			size = (REG_GET_FIELD(viewport, SCL0_VIEWPORT_SIZE, VIEWPORT_HEIGHT) *