Re: [PATCH v4 2/2] drm/bridge: Add Lontium LT9611C(EX/UXD) MIPI DSI to HDMI driver

[Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>]

On Wed, May 06, 2026 at 05:51:00PM +0800, syyang@lontium.com wrote:
> From: Sunyun Yang <syyang@lontium.com>
> 
> LT9611C(EX/UXD) is an I2C-controlled chip that Receiver signal/dual port
> mipi dsi and output hdmi, differences in hardware features:
> - LT9611C: supports 1-port mipi dsi to hdmi 1.4
> - LT9611EX: supports 2-port mipi dsi to hdmi 1.4
> - LT9611UXD: supports 2-port mipi dsi to hdmi 1.4/2.0
> 
> Signed-off-by: Sunyun Yang <syyang@lontium.com>
> ---
>  drivers/gpu/drm/bridge/Kconfig           |   18 +
>  drivers/gpu/drm/bridge/Makefile          |    1 +
>  drivers/gpu/drm/bridge/lontium-lt9611c.c | 1211 ++++++++++++++++++++++
>  3 files changed, 1230 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/lontium-lt9611c.c
> 
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index c3209b0f4678..32b85a2a65d9 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -177,6 +177,24 @@ config DRM_LONTIUM_LT9611
>  	  HDMI signals
>  	  Please say Y if you have such hardware.
>  
> +config DRM_LONTIUM_LT9611C
> +	tristate "Lontium LT9611C DSI/HDMI bridge"
> +	select SND_SOC_HDMI_CODEC if SND_SOC
> +	depends on OF
> +	select CRC8
> +	select FW_LOADER
> +	select DRM_PANEL_BRIDGE
> +	select DRM_KMS_HELPER
> +	select DRM_MIPI_DSI
> +	select DRM_DISPLAY_HELPER
> +	select DRM_DISPLAY_HDMI_STATE_HELPER
> +	select REGMAP_I2C
> +	help
> +	  Driver for Lontium DSI to HDMI bridge
> +	  chip driver that converts dual DSI and I2S to
> +	  HDMI signals
> +	  Please say Y if you have such hardware.
> +
>  config DRM_LONTIUM_LT9611UXC
>  	tristate "Lontium LT9611UXC DSI/HDMI bridge"
>  	select SND_SOC_HDMI_CODEC if SND_SOC
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index beab5b695a6e..92688be9692f 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -16,6 +16,7 @@ obj-$(CONFIG_DRM_ITE_IT6505) += ite-it6505.o
>  obj-$(CONFIG_DRM_LONTIUM_LT8912B) += lontium-lt8912b.o
>  obj-$(CONFIG_DRM_LONTIUM_LT9211) += lontium-lt9211.o
>  obj-$(CONFIG_DRM_LONTIUM_LT9611) += lontium-lt9611.o
> +obj-$(CONFIG_DRM_LONTIUM_LT9611C) += lontium-lt9611c.o
>  obj-$(CONFIG_DRM_LONTIUM_LT9611UXC) += lontium-lt9611uxc.o
>  obj-$(CONFIG_DRM_LONTIUM_LT8713SX) += lontium-lt8713sx.o
>  obj-$(CONFIG_DRM_LVDS_CODEC) += lvds-codec.o
> diff --git a/drivers/gpu/drm/bridge/lontium-lt9611c.c b/drivers/gpu/drm/bridge/lontium-lt9611c.c
> new file mode 100644
> index 000000000000..3131f4a32dfd
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/lontium-lt9611c.c
> @@ -0,0 +1,1211 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2026 Lontium Semiconductor, Inc.
> + */
> +
> +#include <linux/crc8.h>
> +#include <linux/firmware.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/interrupt.h>
> +#include <linux/media-bus-format.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/of_graph.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_bridge.h>
> +#include <drm/drm_connector.h>
> +#include <drm/drm_drv.h>
> +#include <drm/drm_edid.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_modes.h>
> +#include <drm/drm_of.h>
> +#include <drm/drm_print.h>
> +#include <drm/drm_probe_helper.h>
> +#include <drm/display/drm_hdmi_audio_helper.h>
> +#include <drm/display/drm_hdmi_state_helper.h>
> +#include <sound/hdmi-codec.h>
> +
> +#define FW_SIZE (64 * 1024)
> +#define LT_PAGE_SIZE 256
> +#define FW_FILE  "lt9611c_fw.bin"

So, this file doesn't have any subdir (like all other Lontium firmware
files), but then you submit a file to linux-firmware with the Lontium/
subdir. Could you please settle on one location?

> +#define LT9611C_CRC_POLYNOMIAL 0x31
> +#define LT9611C_PAGE_CONTROL 0xff
> +

[...]

> +
> +static const struct drm_bridge_funcs lt9611c_bridge_funcs = {
> +	.attach = lt9611c_bridge_attach,
> +	.detect = lt9611c_bridge_detect,
> +	.edid_read = lt9611c_bridge_edid_read,
> +	.atomic_enable = lt9611c_bridge_atomic_enable,

There is .atomic_enable, but no atomic state management here. Was it
actually tested?

> +

-- 
With best wishes
Dmitry