drm/radeon/hdmi: make sure we have an afmt block assigned

Prevents a segfault if an afmt block is not assigned to the
encoder such as in the LVDS or eDP case.

Fixes:
https://bugs.freedesktop.org/show_bug.cgi?id=66714

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org

drivers/gpu/drm/radeon/evergreen_hdmi.c

@@ -177,6 +177,9 @@ void evergreen_hdmi_setmode(struct drm_encoder *encoder, struct drm_display_mode
 	uint32_t offset;
 	ssize_t err;
 
+	if (!dig || !dig->afmt)
+		return;
+
 	/* Silent, r600_hdmi_enable will raise WARN for us */
 	if (!dig->afmt->enabled)
 		return;
@@ -280,6 +283,9 @@ void evergreen_hdmi_enable(struct drm_encoder *encoder, bool enable)
 	struct radeon_encoder *radeon_encoder = to_radeon_encoder(encoder);
 	struct radeon_encoder_atom_dig *dig = radeon_encoder->enc_priv;
 
+	if (!dig || !dig->afmt)
+		return;
+
 	/* Silent, r600_hdmi_enable will raise WARN for us */
 	if (enable && dig->afmt->enabled)
 		return;

drivers/gpu/drm/radeon/r600_hdmi.c

@@ -266,6 +266,9 @@ void r600_hdmi_setmode(struct drm_encoder *encoder, struct drm_display_mode *mod
 	uint32_t offset;
 	ssize_t err;
 
+	if (!dig || !dig->afmt)
+		return;
+
 	/* Silent, r600_hdmi_enable will raise WARN for us */
 	if (!dig->afmt->enabled)
 		return;
@@ -448,6 +451,9 @@ void r600_hdmi_enable(struct drm_encoder *encoder, bool enable)
 	struct radeon_encoder_atom_dig *dig = radeon_encoder->enc_priv;
 	u32 hdmi = HDMI0_ERROR_ACK;
 
+	if (!dig || !dig->afmt)
+		return;
+
 	/* Silent, r600_hdmi_enable will raise WARN for us */
 	if (enable && dig->afmt->enabled)
 		return;