drm/radeon/kms/atom: bios scratch reg handling updates

- Add missing DFP6 connection state handling
- crtc routing bits not used on DCE4+

Noticed by sylware on phoronix.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/radeon_atombios.c

@@ -2931,6 +2931,20 @@ radeon_atombios_connected_scratch_regs(struct drm_connector *connector,
 			bios_6_scratch &= ~ATOM_S6_ACC_REQ_DFP5;
 		}
 	}
+	if ((radeon_encoder->devices & ATOM_DEVICE_DFP6_SUPPORT) &&
+	    (radeon_connector->devices & ATOM_DEVICE_DFP6_SUPPORT)) {
+		if (connected) {
+			DRM_DEBUG_KMS("DFP6 connected\n");
+			bios_0_scratch |= ATOM_S0_DFP6;
+			bios_3_scratch |= ATOM_S3_DFP6_ACTIVE;
+			bios_6_scratch |= ATOM_S6_ACC_REQ_DFP6;
+		} else {
+			DRM_DEBUG_KMS("DFP6 disconnected\n");
+			bios_0_scratch &= ~ATOM_S0_DFP6;
+			bios_3_scratch &= ~ATOM_S3_DFP6_ACTIVE;
+			bios_6_scratch &= ~ATOM_S6_ACC_REQ_DFP6;
+		}
+	}
 
 	if (rdev->family >= CHIP_R600) {
 		WREG32(R600_BIOS_0_SCRATCH, bios_0_scratch);
@@ -2951,6 +2965,9 @@ radeon_atombios_encoder_crtc_scratch_regs(struct drm_encoder *encoder, int crtc)
 	struct radeon_encoder *radeon_encoder = to_radeon_encoder(encoder);
 	uint32_t bios_3_scratch;
 
+	if (ASIC_IS_DCE4(rdev))
+		return;
+
 	if (rdev->family >= CHIP_R600)
 		bios_3_scratch = RREG32(R600_BIOS_3_SCRATCH);
 	else