drm/bridge: synopsys: dw-mipi-dsi: Add input bus format negotiation support

Introduce ->get_input_bus_fmts() callback to struct dw_mipi_dsi_plat_data
so that vendor drivers can implement specific methods to get input bus
formats for Synopsys DW MIPI DSI.

While at it, implement a generic callback for ->atomic_get_input_bus_fmts(),
where we try to get the input bus formats through pdata->get_input_bus_fmts()
first.  If it's unavailable, fall back to the only format - MEDIA_BUS_FMT_FIXED,
which matches the default behavior if ->atomic_get_input_bus_fmts() is not
implemented as ->atomic_get_input_bus_fmts()'s kerneldoc indicates.
Signed-off-by: Liu Ying <victor.liu@nxp.com>
Reviewed-by: Robert Foss <rfoss@kernel.org>
Signed-off-by: Robert Foss <rfoss@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230821034008.3876938-3-victor.liu@nxp.com

drivers/gpu/drm/bridge/synopsys/dw-mipi-dsi.c

@@ -12,6 +12,7 @@
 #include <linux/component.h>
 #include <linux/debugfs.h>
 #include <linux/iopoll.h>
+#include <linux/media-bus-format.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
@@ -538,6 +539,34 @@ static const struct mipi_dsi_host_ops dw_mipi_dsi_host_ops = {
 	.transfer = dw_mipi_dsi_host_transfer,
 };
 
+static u32 *
+dw_mipi_dsi_bridge_atomic_get_input_bus_fmts(struct drm_bridge *bridge,
+					     struct drm_bridge_state *bridge_state,
+					     struct drm_crtc_state *crtc_state,
+					     struct drm_connector_state *conn_state,
+					     u32 output_fmt,
+					     unsigned int *num_input_fmts)
+{
+	struct dw_mipi_dsi *dsi = bridge_to_dsi(bridge);
+	const struct dw_mipi_dsi_plat_data *pdata = dsi->plat_data;
+	u32 *input_fmts;
+
+	if (pdata->get_input_bus_fmts)
+		return pdata->get_input_bus_fmts(pdata->priv_data,
+						 bridge, bridge_state,
+						 crtc_state, conn_state,
+						 output_fmt, num_input_fmts);
+
+	/* Fall back to MEDIA_BUS_FMT_FIXED as the only input format. */
+	input_fmts = kmalloc(sizeof(*input_fmts), GFP_KERNEL);
+	if (!input_fmts)
+		return NULL;
+	input_fmts[0] = MEDIA_BUS_FMT_FIXED;
+	*num_input_fmts = 1;
+
+	return input_fmts;
+}
+
 static void dw_mipi_dsi_video_mode_config(struct dw_mipi_dsi *dsi)
 {
 	u32 val;
@@ -1006,6 +1035,7 @@ static int dw_mipi_dsi_bridge_attach(struct drm_bridge *bridge,
 static const struct drm_bridge_funcs dw_mipi_dsi_bridge_funcs = {
 	.atomic_duplicate_state	= drm_atomic_helper_bridge_duplicate_state,
 	.atomic_destroy_state	= drm_atomic_helper_bridge_destroy_state,
+	.atomic_get_input_bus_fmts = dw_mipi_dsi_bridge_atomic_get_input_bus_fmts,
 	.atomic_reset		= drm_atomic_helper_bridge_reset,
 	.atomic_pre_enable	= dw_mipi_dsi_bridge_atomic_pre_enable,
 	.atomic_enable		= dw_mipi_dsi_bridge_atomic_enable,

include/drm/bridge/dw_mipi_dsi.h

@@ -11,7 +11,10 @@
 
 #include <linux/types.h>
 
+#include <drm/drm_atomic.h>
 #include <drm/drm_bridge.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_crtc.h>
 #include <drm/drm_modes.h>
 
 struct drm_display_mode;
@@ -56,6 +59,14 @@ struct dw_mipi_dsi_plat_data {
 					   unsigned long mode_flags,
 					   u32 lanes, u32 format);
 
+	u32 *(*get_input_bus_fmts)(void *priv_data,
+				   struct drm_bridge *bridge,
+				   struct drm_bridge_state *bridge_state,
+				   struct drm_crtc_state *crtc_state,
+				   struct drm_connector_state *conn_state,
+				   u32 output_fmt,
+				   unsigned int *num_input_fmts);
+
 	const struct dw_mipi_dsi_phy_ops *phy_ops;
 	const struct dw_mipi_dsi_host_ops *host_ops;