Re: [PATCH v7 2/3] drm/bridge: imx: Add i.MX93 parallel display format configuration support

[Liu Ying <victor.liu@nxp.com>]

Hi Marco,

On 12/02/2025, Marco Felsch wrote:
> From: Liu Ying <victor.liu@nxp.com>
> 
> 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.
> 
> Signed-off-by: Liu Ying <victor.liu@nxp.com>
> [m.felsch@pengutronix.de: port to v6.18-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: make use of reg property]
> [m.felsch@pengutronix.de: add bus-width support]
> Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
> ---
>  drivers/gpu/drm/bridge/imx/Kconfig      |  11 ++
>  drivers/gpu/drm/bridge/imx/Makefile     |   1 +
>  drivers/gpu/drm/bridge/imx/imx93-pdfc.c | 227 ++++++++++++++++++++++++++++++++
>  3 files changed, 239 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/imx/Kconfig b/drivers/gpu/drm/bridge/imx/Kconfig
> index 9a480c6abb856276df9b71d23b39a43b3a9c542d..28fd7a00473a0ec50bf0ffb5d50972abc209ceec 100644
> --- a/drivers/gpu/drm/bridge/imx/Kconfig
> +++ b/drivers/gpu/drm/bridge/imx/Kconfig
> @@ -88,4 +88,15 @@ config DRM_IMX93_MIPI_DSI
>  	  Choose this to enable MIPI DSI controller found in Freescale i.MX93
>  	  processor.
>  
> +config DRM_IMX93_PARALLEL_DISP_FMT_CONFIG
> +	tristate "NXP i.MX91/i.MX93 parallel display format configuration"
> +	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
> diff --git a/drivers/gpu/drm/bridge/imx/Makefile b/drivers/gpu/drm/bridge/imx/Makefile
> index dd5d4858480663bade98bd58039d1cb6f8aa18da..f4ccc5cbef72a576443d5fecf666b76dfba8aa94 100644
> --- a/drivers/gpu/drm/bridge/imx/Makefile
> +++ b/drivers/gpu/drm/bridge/imx/Makefile
> @@ -8,3 +8,4 @@ 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_CONFIG) += imx93-pdfc.o
> diff --git a/drivers/gpu/drm/bridge/imx/imx93-pdfc.c b/drivers/gpu/drm/bridge/imx/imx93-pdfc.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..624389def0ac3f24158edc64a8913375a4cc2f12
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/imx/imx93-pdfc.c
> @@ -0,0 +1,227 @@
> +// 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_address.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>
> +#include <drm/drm_print.h>

Drop this header file if you won't use DRM_DEV_DEBUG_DRIVER() in v5.

> +
> +#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 drm_bridge *next_bridge;
> +	struct device *dev;
> +	struct regmap *regmap;
> +	u64 disp_mux_reg_off;
> +	u32 phy_bus_width;
> +};
> +
> +static int
> +imx93_pdfc_bridge_attach(struct drm_bridge *bridge, struct drm_encoder *encoder,
> +			 enum drm_bridge_attach_flags flags)
> +{
> +	struct imx93_pdfc *pdfc = bridge->driver_private;
> +
> +	return drm_bridge_attach(bridge->encoder, pdfc->next_bridge, bridge, flags);
> +}
> +
> +static void imx93_pdfc_bridge_atomic_enable(struct drm_bridge *bridge,
> +					    struct drm_atomic_state *state)
> +{
> +	struct imx93_pdfc *pdfc = bridge->driver_private;
> +	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:
> +		val = FORMAT_RGB888_TO_RGB888;
> +		if (pdfc->phy_bus_width == 18) {
> +			/*
> +			 * Can be valid if physical bus limitation exist,

s/exist/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, pdfc->disp_mux_reg_off, mask, val);
> +}
> +
> +static const u32 imx93_pdfc_bus_output_fmts[] = {
> +	MEDIA_BUS_FMT_RGB888_1X24,
> +	MEDIA_BUS_FMT_RGB666_1X18,
> +	MEDIA_BUS_FMT_RGB565_1X16,
> +	MEDIA_BUS_FMT_FIXED
> +};
> +
> +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(sizeof(*input_fmts), GFP_KERNEL);
> +	if (!input_fmts)
> +		return NULL;
> +
> +	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;
> +	}
> +
> +	*num_input_fmts = 1;
> +
> +	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->driver_private;
> +
> +	switch (bridge_state->output_bus_cfg.format) {
> +	case MEDIA_BUS_FMT_RGB888_1X24:
> +	case MEDIA_BUS_FMT_RGB666_1X18:
> +	case MEDIA_BUS_FMT_RGB565_1X16:

The case MEDIA_BUS_FMT_FIXED is also valid.

> +		return 0;
> +	default:
> +		dev_warn(pdfc->dev, "Unsupported output bus format: 0x%x\n",
> +			 bridge_state->output_bus_cfg.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_reset		= drm_atomic_helper_bridge_reset,
> +};
> +
> +static int imx93_pdfc_bridge_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	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");
> +
> +	err = of_property_read_reg(dev->of_node, 0, &pdfc->disp_mux_reg_off, NULL);
> +	if (err)
> +		return dev_err_probe(dev, err,
> +				     "failed to get display-mux reg\n");
> +
> +	/* No limits per default */
> +	pdfc->phy_bus_width = 24;
> +
> +	/* Get output ep (port1/endpoint0) */
> +	ep = of_graph_get_endpoint_by_regs(dev->of_node, 1, 0);

Nit: DT binding just defines endpoint not endpoint0, so set the reg parameter
to -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");
> +	}
> +
> +	pdfc->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 1, 0);
> +	if (IS_ERR(pdfc->next_bridge))
> +		return dev_err_probe(dev, PTR_ERR(pdfc->next_bridge),
> +				     "failed to get next bridge\n");
> +
> +	pdfc->dev = dev;
> +	pdfc->bridge.driver_private = pdfc;
> +	pdfc->bridge.of_node = dev->of_node;
> +	pdfc->bridge.type = DRM_MODE_CONNECTOR_DPI;
> +
> +	return devm_drm_bridge_add(dev, &pdfc->bridge);
> +}
> +
> +static const struct of_device_id imx93_pdfc_dt_ids[] = {
> +	{ .compatible = "nxp,imx93-pdfc", },

The cover letter and Kconfig say that both i.MX91 and i.MX93 are supported,
so need an additional compatible string for i.MX91?

> +	{ /* 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");
> 


-- 
Regards,
Liu Ying