drm/bridge: tc358767: Add format negotiation hooks for DPI/DSI to (e)DP

With new connector model, tc358767 will not create the connector, when
DRM_BRIDGE_ATTACH_NO_CONNECTOR is set and display-controller driver will
rely on format negotiation to setup the encoder format.

Add the missing bus format negotiation hooks in the
drm_bridge_funcs to complete DRM_BRIDGE_ATTACH_NO_CONNECTOR support.

Output format, for DPI/DSI to DP, is selected to
MEDIA_BUS_FMT_RGB888_1X24 as default, keeping in mind what the older
model used to support.

Reported-by: Jan Kiszka <[e-mail]>
Closes: https://lore.kernel.org/all/[e-mail]/
Signed-off-by: Aradhya Bhatia <[e-mail]>
Signed-off-by: Tomi Valkeinen <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]
Signed-off-by: Dmitry Baryshkov <[e-mail]>

drivers/gpu/drm/bridge/tc358767.c

···
 }
 
 #define MAX_INPUT_SEL_FORMATS	1
+#define MAX_OUTPUT_SEL_FORMATS	1
 
 static u32 *
 tc_dpi_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
···
 	*num_input_fmts = 1;
 
 	return input_fmts;
+}
+
+static u32 *
+tc_edp_atomic_get_output_bus_fmts(struct drm_bridge *bridge,
+				  struct drm_bridge_state *bridge_state,
+				  struct drm_crtc_state *crtc_state,
+				  struct drm_connector_state *conn_state,
+				  unsigned int *num_output_fmts)
+{
+	u32 *output_fmts;
+
+	*num_output_fmts = 0;
+
+	output_fmts = kcalloc(MAX_OUTPUT_SEL_FORMATS, sizeof(*output_fmts),
+			      GFP_KERNEL);
+	if (!output_fmts)
+		return NULL;
+
+	output_fmts[0] = MEDIA_BUS_FMT_RGB888_1X24;
+	*num_output_fmts = 1;
+
+	return output_fmts;
 }
 
 static const struct drm_bridge_funcs tc_dpi_bridge_funcs = {
···
 	.atomic_duplicate_state = drm_atomic_helper_bridge_duplicate_state,
 	.atomic_destroy_state = drm_atomic_helper_bridge_destroy_state,
 	.atomic_reset = drm_atomic_helper_bridge_reset,
+	.atomic_get_input_bus_fmts = drm_atomic_helper_bridge_propagate_bus_fmt,
+	.atomic_get_output_bus_fmts = tc_edp_atomic_get_output_bus_fmts,
 };
 
 static bool tc_readable_reg(struct device *dev, unsigned int reg)