drm/bridge: imx: Add i.MX93 parallel display format configuration support

NXP i.MX93 mediamix blk-ctrl contains one DISPLAY_MUX register which
configures parallel display format by using the "PARALLEL_DISP_FORMAT"
field. Add a DRM bridge driver to support the display format configuration.

[m.felsch@pengutronix.de: port to v7.0-rc1]
[m.felsch@pengutronix.de: add review feedback (Alexander)]
[m.felsch@pengutronix.de: fix to short Kconfig description (checkpath)]
[m.felsch@pengutronix.de: use "GPL" instead of "GPL v2" (checkpatch)]
[m.felsch@pengutronix.de: add bus-width support]
[ Liu Ying: Port to drm-misc/drm-misc-next(v7.2-rc2 based) ]
[ Liu Ying: Add nxp,imx91-pdfc compatible string ]
[ Liu Ying: Call drm_bridge_get() for next_bridge ]
[ Liu Ying: Reject unsupported output bus fmt in .atomic_get_input_bus_fmts() ]

Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
Reviewed-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>
Link: https://patch.msgid.link/20260723-v6-18-topic-imx93-parallel-display-v13-1-ccf3f9bbc0fc@nxp.com
Signed-off-by: Liu Ying <victor.liu@nxp.com>

drivers/gpu/drm/bridge/imx/Kconfig

@@ -107,4 +107,15 @@ config DRM_IMX93_MIPI_DSI
 	  Choose this to enable MIPI DSI controller found in Freescale i.MX93
 	  processor.
 
+config DRM_IMX93_PARALLEL_DISP_FMT_CONVERTER
+	tristate "NXP i.MX91/i.MX93 parallel display format converter"
+	depends on OF
+	select DRM_KMS_HELPER
+	help
+	  On i.MX93 and i.MX91 SoCs the parallel display format output is
+	  controlled via the MEDIAMIX BLK-CTRL DISPLAY_MUX.
+
+	  Say 'Y' or 'M' if you use the parallel display output path on a
+	  i.MX93 or i.MX91 SoC.
+
 endif # ARCH_MXC || COMPILE_TEST

drivers/gpu/drm/bridge/imx/Makefile

@@ -10,3 +10,4 @@ obj-$(CONFIG_DRM_IMX8QXP_PIXEL_COMBINER) += imx8qxp-pixel-combiner.o
 obj-$(CONFIG_DRM_IMX8QXP_PIXEL_LINK) += imx8qxp-pixel-link.o
 obj-$(CONFIG_DRM_IMX8QXP_PIXEL_LINK_TO_DPI) += imx8qxp-pxl2dpi.o
 obj-$(CONFIG_DRM_IMX93_MIPI_DSI) += imx93-mipi-dsi.o
+obj-$(CONFIG_DRM_IMX93_PARALLEL_DISP_FMT_CONVERTER) += imx93-pdfc.o

drivers/gpu/drm/bridge/imx/imx93-pdfc.c

@@ -0,0 +1,222 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+/*
+ * Copyright 2022-2025 NXP
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bits.h>
+#include <linux/media-bus-format.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_graph.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#include <drm/drm_atomic_state_helper.h>
+#include <drm/drm_bridge.h>
+
+#define IMX93_DISPLAY_MUX_REG		0x60
+#define PARALLEL_DISP_FORMAT		GENMASK(10, 8)
+#define FORMAT_RGB888_TO_RGB888		FIELD_PREP(PARALLEL_DISP_FORMAT, 0)
+#define FORMAT_RGB888_TO_RGB666		FIELD_PREP(PARALLEL_DISP_FORMAT, 1)
+#define FORMAT_RGB565_TO_RGB565		FIELD_PREP(PARALLEL_DISP_FORMAT, 2)
+
+struct imx93_pdfc {
+	struct drm_bridge bridge;
+	struct device *dev;
+	struct regmap *regmap;
+	u32 phy_bus_width;
+};
+
+static struct imx93_pdfc *bridge_to_imx93_pdfc(struct drm_bridge *bridge)
+{
+	return container_of(bridge, struct imx93_pdfc, bridge);
+}
+
+static int
+imx93_pdfc_bridge_attach(struct drm_bridge *bridge, struct drm_encoder *encoder,
+			 enum drm_bridge_attach_flags flags)
+{
+	return drm_bridge_attach(bridge->encoder, bridge->next_bridge, bridge, flags);
+}
+
+static void imx93_pdfc_bridge_atomic_enable(struct drm_bridge *bridge,
+					    struct drm_atomic_commit *state)
+{
+	struct imx93_pdfc *pdfc = bridge_to_imx93_pdfc(bridge);
+	const struct drm_bridge_state *bridge_state;
+	unsigned int mask = PARALLEL_DISP_FORMAT;
+	unsigned int val;
+
+	bridge_state = drm_atomic_get_new_bridge_state(state, bridge);
+
+	switch (bridge_state->output_bus_cfg.format) {
+	case MEDIA_BUS_FMT_RGB888_1X24:
+	case MEDIA_BUS_FMT_FIXED:
+		val = FORMAT_RGB888_TO_RGB888;
+		if (pdfc->phy_bus_width == 18) {
+			/*
+			 * Can be valid if physical bus limitation exists,
+			 * therefore use dev_dbg().
+			 */
+			dev_dbg(pdfc->dev, "Truncate two LSBs from each color\n");
+			val = FORMAT_RGB888_TO_RGB666;
+		}
+		break;
+	case MEDIA_BUS_FMT_RGB666_1X18:
+		val = FORMAT_RGB888_TO_RGB666;
+		break;
+	case MEDIA_BUS_FMT_RGB565_1X16:
+		val = FORMAT_RGB565_TO_RGB565;
+		break;
+	}
+
+	regmap_update_bits(pdfc->regmap, IMX93_DISPLAY_MUX_REG, mask, val);
+}
+
+/* TODO: Add YUV formats */
+static const u32 imx93_pdfc_bus_output_fmts[] = {
+	MEDIA_BUS_FMT_FIXED,
+	MEDIA_BUS_FMT_RGB888_1X24,
+	MEDIA_BUS_FMT_RGB666_1X18,
+	MEDIA_BUS_FMT_RGB565_1X16,
+};
+
+static bool imx93_pdfc_bus_output_fmt_supported(u32 fmt)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(imx93_pdfc_bus_output_fmts); i++) {
+		if (imx93_pdfc_bus_output_fmts[i] == fmt)
+			return true;
+	}
+
+	return false;
+}
+
+static u32 *
+imx93_pdfc_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)
+{
+	u32 *input_fmts;
+
+	*num_input_fmts = 0;
+
+	if (!imx93_pdfc_bus_output_fmt_supported(output_fmt))
+		return NULL;
+
+	input_fmts = kmalloc_obj(*input_fmts);
+	if (!input_fmts)
+		return NULL;
+
+	*num_input_fmts = 1;
+
+	switch (output_fmt) {
+	case MEDIA_BUS_FMT_RGB888_1X24:
+	case MEDIA_BUS_FMT_RGB565_1X16:
+		input_fmts[0] = output_fmt;
+		break;
+	case MEDIA_BUS_FMT_RGB666_1X18:
+	case MEDIA_BUS_FMT_FIXED:
+		input_fmts[0] = MEDIA_BUS_FMT_RGB888_1X24;
+		break;
+	}
+
+	return input_fmts;
+}
+
+static int imx93_pdfc_bridge_atomic_check(struct drm_bridge *bridge,
+					  struct drm_bridge_state *bridge_state,
+					  struct drm_crtc_state *crtc_state,
+					  struct drm_connector_state *conn_state)
+{
+	struct imx93_pdfc *pdfc = bridge_to_imx93_pdfc(bridge);
+	u32 format = bridge_state->output_bus_cfg.format;
+
+	if (imx93_pdfc_bus_output_fmt_supported(format))
+		return 0;
+
+	dev_warn(pdfc->dev, "Unsupported output bus format: 0x%x\n", format);
+
+	return -EINVAL;
+}
+
+static const struct drm_bridge_funcs funcs = {
+	.attach			= imx93_pdfc_bridge_attach,
+	.atomic_enable		= imx93_pdfc_bridge_atomic_enable,
+	.atomic_duplicate_state	= drm_atomic_helper_bridge_duplicate_state,
+	.atomic_destroy_state	= drm_atomic_helper_bridge_destroy_state,
+	.atomic_get_input_bus_fmts	= imx93_pdfc_bridge_atomic_get_input_bus_fmts,
+	.atomic_check		= imx93_pdfc_bridge_atomic_check,
+	.atomic_create_state	= drm_atomic_helper_bridge_create_state,
+};
+
+static int imx93_pdfc_bridge_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct drm_bridge *next_bridge;
+	struct imx93_pdfc *pdfc;
+	struct device_node *ep;
+	int err;
+
+	pdfc = devm_drm_bridge_alloc(dev, struct imx93_pdfc, bridge, &funcs);
+	if (IS_ERR(pdfc))
+		return PTR_ERR(pdfc);
+
+	pdfc->regmap = syscon_node_to_regmap(dev->of_node->parent);
+	if (IS_ERR(pdfc->regmap))
+		return dev_err_probe(dev, PTR_ERR(pdfc->regmap),
+				     "failed to get regmap\n");
+
+	/* No limits per default */
+	pdfc->phy_bus_width = 24;
+
+	/* Get output ep (port1/endpoint) */
+	ep = of_graph_get_endpoint_by_regs(dev->of_node, 1, -1);
+	if (ep) {
+		err = of_property_read_u32(ep, "bus-width", &pdfc->phy_bus_width);
+		of_node_put(ep);
+
+		/* bus-width is optional but it must have valid data if present */
+		if (err && err != -EINVAL)
+			return dev_err_probe(dev, err,
+					     "failed to query bus-width\n");
+	}
+
+	next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 1, 0);
+	if (IS_ERR(next_bridge))
+		return dev_err_probe(dev, PTR_ERR(next_bridge),
+				     "failed to get next bridge\n");
+	pdfc->dev = dev;
+	pdfc->bridge.of_node = dev->of_node;
+	pdfc->bridge.type = DRM_MODE_CONNECTOR_DPI;
+	pdfc->bridge.next_bridge = drm_bridge_get(next_bridge);
+
+	return devm_drm_bridge_add(dev, &pdfc->bridge);
+}
+
+static const struct of_device_id imx93_pdfc_dt_ids[] = {
+	{ .compatible = "nxp,imx91-pdfc", },
+	{ .compatible = "nxp,imx93-pdfc", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, imx93_pdfc_dt_ids);
+
+static struct platform_driver imx93_pdfc_bridge_driver = {
+	.probe	= imx93_pdfc_bridge_probe,
+	.driver	= {
+		.of_match_table = imx93_pdfc_dt_ids,
+		.name = "imx93_pdfc",
+	},
+};
+module_platform_driver(imx93_pdfc_bridge_driver);
+
+MODULE_DESCRIPTION("NXP i.MX93 parallel display format configuration driver");
+MODULE_AUTHOR("Liu Ying <victor.liu@nxp.com>");
+MODULE_LICENSE("GPL");