Re: [PATCH 2/2] drm/bridge: Add LT7911EXC edp to mipi bridge driver

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

On Mon, 20 Apr 2026 at 05:34, <syyang@lontium.com> wrote:
>
> From: Sunyun Yang <syyang@lontium.com>
>
> LT7911EXC is a high performance  eDP1.4 to MIPI chip for

MIPI what?

> VR/Display application.
>
> -eDP1.4Receiver
>  1.Support SSC
>  2.Support 1/2/4 lanes
>  3.Support up to 4K@60HzRGB/YCbCr4:4:48bpc
>  4.Support lane swap and PN swap
>
> -MIPI Transmitter
>  1.CompliantwithD-PHY1.2&DSI1.1&CSI-22.0；1 clock lane,
>    and1/2/3/4 configurable data lanes:2.5Gbpsperdatalane
>  2.CompliantwithC-PHY1.0&DSI-21.0&CSI-22.0;
>    1/2/3 configurable data trio；2.5Gsps perdatatrio
>  3.Support1/2configurable ports
>  4.DSISupport16/20/24-bit YCbCr4:2:2,16/18/24/30-bit RGB
>
> 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-lt7911exc.c | 571 +++++++++++++++++++++
>  3 files changed, 590 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/lontium-lt7911exc.c
>
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index c3209b0f4678..bae8cdaea666 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -202,6 +202,24 @@ config DRM_LONTIUM_LT8713SX
>           to 3 configurable Type-C/DP1.4/HDMI2.0 outputs
>           Please say Y if you have such hardware.
>
> +config DRM_LONTIUM_LT9611C

I thought the patch is for LT7911EXC

> +       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_ITE_IT66121
>         tristate "ITE IT66121 HDMI bridge"
>         depends on OF
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index beab5b695a6e..54b293d1663e 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -18,6 +18,7 @@ obj-$(CONFIG_DRM_LONTIUM_LT9211) += lontium-lt9211.o
>  obj-$(CONFIG_DRM_LONTIUM_LT9611) += lontium-lt9611.o
>  obj-$(CONFIG_DRM_LONTIUM_LT9611UXC) += lontium-lt9611uxc.o
>  obj-$(CONFIG_DRM_LONTIUM_LT8713SX) += lontium-lt8713sx.o
> +obj-$(CONFIG_DRM_LONTIUM_LT7911EXC) += lontium-lt7911exc.o

Keep the list sorted, please.

>  obj-$(CONFIG_DRM_LVDS_CODEC) += lvds-codec.o
>  obj-$(CONFIG_DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW) += megachips-stdpxxxx-ge-b850v3-fw.o
>  obj-$(CONFIG_DRM_MICROCHIP_LVDS_SERIALIZER) += microchip-lvds.o
> diff --git a/drivers/gpu/drm/bridge/lontium-lt7911exc.c b/drivers/gpu/drm/bridge/lontium-lt7911exc.c
> new file mode 100644
> index 000000000000..d1c1d9e073ef
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/lontium-lt7911exc.c
> @@ -0,0 +1,571 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2026 Lontium Semiconductor, Inc.
> + */
> +
> +#include <linux/crc32.h>
> +#include <linux/firmware.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/regmap.h>

I think you use more than that.

> +#include <drm/drm_of.h>
> +
> +#define FW_SIZE (64 * 1024)
> +#define LT_PAGE_SIZE 32
> +#define FW_FILE  "LT7911EXC.bin"
> +#define LT7911EXC_PAGE_CONTROL 0xff
> +
> +struct lt7911exc {
> +       struct device *dev;
> +       struct i2c_client *client;
> +       struct drm_bridge bridge;
> +       struct drm_bridge *panel_bridge;

Use next_bridge from struct drm_bridge instead.

> +       struct regmap *regmap;
> +       /* Protects all accesses to registers by stopping the on-chip MCU */
> +       struct mutex ocm_lock;
> +       struct regulator_bulk_data supplies[2];
> +
> +       struct gpio_desc *reset_gpio;
> +       const struct firmware *fw;

Do you need to store it during the runtime? If not, please remove from
the data struct.

> +       int fw_version;
> +       u32 fw_crc;
> +
> +       bool enabled;

What for?

> +};
> +
> +static const struct regmap_range_cfg lt7911exc_ranges[] = {
> +       {
> +               .name = "register_range",
> +               .range_min =  0,
> +               .range_max = 0xffff,

Is it an actual range?

> +               .selector_reg = LT7911EXC_PAGE_CONTROL,
> +               .selector_mask = 0xff,
> +               .selector_shift = 0,
> +               .window_start = 0,
> +               .window_len = 0x100,
> +       },
> +};
> +
> +static const struct regmap_config lt7911exc_regmap_config = {
> +       .reg_bits = 8,
> +       .val_bits = 8,
> +       .max_register = 0xffff,
> +       .ranges = lt7911exc_ranges,
> +       .num_ranges = ARRAY_SIZE(lt7911exc_ranges),
> +};
> +
> +static u32 cal_crc32_custom(const u8 *data, u64 length)
> +{
> +       u32 crc = 0xffffffff;
> +       u8 buf[4];
> +       u64 i;
> +
> +       for (i = 0; i < length; i += 4) {
> +               buf[0] = data[i + 3];
> +               buf[1] = data[i + 2];
> +               buf[2] = data[i + 1];
> +               buf[3] = data[i + 0];
> +               crc = crc32_be(crc, buf, 4);

How is it different from crc32_le()?

> +               }

Wrong alignment.

> +
> +       return crc;
> +}
> +
> +static inline struct lt7911exc *
> +               bridge_to_lt7911exc(struct drm_bridge *bridge)

One line, please.

> +{
> +       return container_of(bridge, struct lt7911exc, bridge);
> +}
> +
> +static int lt7911exc_regulator_enable(struct lt7911exc *lt7911exc)
> +{
> +       int ret;
> +
> +       ret = regulator_enable(lt7911exc->supplies[0].consumer);

If you are not using bulk interface here, why did you declare supplies as bulks?

> +       if (ret < 0)
> +               return ret;
> +
> +       usleep_range(5000, 10000);
> +
> +       ret = regulator_enable(lt7911exc->supplies[1].consumer);
> +       if (ret < 0) {
> +               regulator_disable(lt7911exc->supplies[0].consumer);
> +               return ret;
> +       }
> +
> +       return 0;
> +}
> +
> +static int lt7911exc_regulator_disable(struct lt7911exc *lt7911exc)
> +{
> +       int ret;
> +
> +       ret = regulator_disable(lt7911exc->supplies[1].consumer);
> +       if (ret < 0)
> +               return ret;
> +
> +       ret = regulator_disable(lt7911exc->supplies[0].consumer);
> +       if (ret < 0)
> +               return ret;
> +
> +       return 0;
> +}
> +
> +static void lt7911exc_reset(struct lt7911exc *lt7911exc)
> +{
> +       gpiod_set_value_cansleep(lt7911exc->reset_gpio, 1);
> +       msleep(20);
> +
> +       gpiod_set_value_cansleep(lt7911exc->reset_gpio, 0);
> +       msleep(20);
> +
> +       gpiod_set_value_cansleep(lt7911exc->reset_gpio, 1);

Yep, it's active low. Invert polarities here.

> +       msleep(400);
> +
> +       dev_dbg(lt7911exc->dev, "lt7911exc reset");
> +}
> +
> +static int lt7911exc_parse_dt(struct lt7911exc *lt7911exc)
> +{
> +       int ret;
> +
> +       lt7911exc->supplies[0].supply = "vcc";
> +       lt7911exc->supplies[1].supply = "vdd";
> +
> +       ret = devm_regulator_bulk_get(lt7911exc->dev, 2, lt7911exc->supplies);
> +       if (ret) {
> +               dev_err(lt7911exc->dev, "failed get regulator\n");
> +               return ret;

return dev_err_probe();

> +       }
> +
> +       lt7911exc->reset_gpio = devm_gpiod_get(lt7911exc->dev, "reset", GPIOD_OUT_LOW);
> +       if (IS_ERR(lt7911exc->reset_gpio)) {
> +               dev_err(lt7911exc->dev, "failed to acquire reset gpio\n");

return dev_err_probe();

> +               return PTR_ERR(lt7911exc->reset_gpio);
> +       }
> +
> +       return 0;
> +}
> +
> +static int lt7911exc_read_version(struct lt7911exc *lt7911exc)
> +{
> +       u8 buf[2];
> +       int ret;
> +
> +       ret = regmap_bulk_read(lt7911exc->regmap, 0xe081, buf, 3);

Do you see a buffer overflow here?

> +       if (ret)
> +               return ret;
> +
> +       return (buf[0] << 16) | (buf[1] << 8) | buf[2];
> +}
> +
> +static void lt7911exc_lock(struct lt7911exc *lt7911exc)
> +{
> +       mutex_lock(&lt7911exc->ocm_lock);
> +       regmap_write(lt7911exc->regmap, 0xe0ee, 0x01);
> +}
> +
> +static void lt7911exc_unlock(struct lt7911exc *lt7911exc)
> +{
> +       regmap_write(lt7911exc->regmap, 0xe0ee, 0x00);
> +       mutex_unlock(&lt7911exc->ocm_lock);
> +}
> +
> +static int lt7911exc_prepare_firmware_data(struct lt7911exc *lt7911exc)
> +{
> +       struct device *dev = lt7911exc->dev;
> +       int ret;
> +       u8 *buffer;
> +       size_t total_size = FW_SIZE - 4;
> +
> +       ret = request_firmware(&lt7911exc->fw, FW_FILE, dev);
> +       if (ret) {
> +               dev_err(dev, "failed load file '%s', error type %d\n", FW_FILE, ret);
> +               return ret;
> +       }
> +
> +       if (lt7911exc->fw->size > total_size) {
> +               dev_err(dev, "firmware too large (%zu > %zu)\n", lt7911exc->fw->size, total_size);
> +               release_firmware(lt7911exc->fw);
> +               lt7911exc->fw = NULL;
> +               return -EINVAL;
> +       }
> +
> +       dev_dbg(dev, "firmware size: %zu bytes\n", lt7911exc->fw->size);
> +
> +       buffer = kzalloc(total_size, GFP_KERNEL);
> +       if (!buffer) {
> +               release_firmware(lt7911exc->fw);
> +               lt7911exc->fw = NULL;
> +               return -ENOMEM;
> +       }
> +
> +       memset(buffer, 0xff, total_size);
> +       memcpy(buffer, lt7911exc->fw->data, lt7911exc->fw->size);
> +
> +       lt7911exc->fw_crc = cal_crc32_custom(buffer, total_size);
> +       dev_dbg(dev, "firmware crc: 0x%08x\n", lt7911exc->fw_crc);
> +
> +       kfree(buffer);
> +       return 0;
> +}
> +
> +static void lt7911exc_block_erase(struct lt7911exc *lt7911exc)
> +{
> +       struct device *dev = lt7911exc->dev;
> +       const u32 addr = 0x00;
> +
> +       const struct reg_sequence seq_write[] = {
> +               REG_SEQ0(0xe0ee, 0x01),
> +               REG_SEQ0(0xe054, 0x01),
> +               REG_SEQ0(0xe055, 0x06),
> +               REG_SEQ0(0xe051, 0x01),
> +               REG_SEQ0(0xe051, 0x00),
> +               REG_SEQ0(0xe054, 0x05),
> +               REG_SEQ0(0xe055, 0xd8),
> +               REG_SEQ0(0xe05a, (addr >> 16) & 0xff),
> +               REG_SEQ0(0xe05b, (addr >> 8) & 0xff),
> +               REG_SEQ0(0xe05c, addr & 0xff),
> +               REG_SEQ0(0xe051, 0x01),
> +               REG_SEQ0(0xe050, 0x00),
> +       };
> +
> +       regmap_multi_reg_write(lt7911exc->regmap, seq_write, ARRAY_SIZE(seq_write));
> +
> +       msleep(200);
> +       dev_dbg(dev, "erase flash done.\n");
> +}
> +
> +static void lt7911exc_prog_init(struct lt7911exc *lt7911exc, u64 addr)
> +{
> +       const struct reg_sequence seq_write[] = {
> +               REG_SEQ0(0xe0ee, 0x01),
> +               REG_SEQ0(0xe05f, 0x01),
> +               REG_SEQ0(0xe05a, (addr >> 16) & 0xff),
> +               REG_SEQ0(0xe05b, (addr >> 8) & 0xff),
> +               REG_SEQ0(0xe05c, addr & 0xff),
> +       };
> +
> +       regmap_multi_reg_write(lt7911exc->regmap, seq_write, ARRAY_SIZE(seq_write));
> +}
> +
> +static int lt7911exc_write_data(struct lt7911exc *lt7911exc, u64 addr)
> +{
> +       struct device *dev = lt7911exc->dev;
> +       int ret;
> +       int page = 0, num = 0, page_len = 0;
> +       u64 size, offset;
> +       const u8 *data;
> +
> +       data = lt7911exc->fw->data;
> +       size = lt7911exc->fw->size;
> +       page = (size + LT_PAGE_SIZE - 1) / LT_PAGE_SIZE;
> +       if (page * LT_PAGE_SIZE > FW_SIZE) {
> +               dev_err(dev, "firmware size out of range\n");
> +               return -EINVAL;
> +       }
> +
> +       dev_dbg(dev, "%u pages, total size %llu byte\n", page, size);
> +
> +       for (num = 0; num < page; num++) {
> +               offset = num * LT_PAGE_SIZE;
> +               page_len = (offset + LT_PAGE_SIZE <= size) ? LT_PAGE_SIZE : (size - offset);
> +               lt7911exc_prog_init(lt7911exc, addr);
> +
> +               ret = regmap_raw_write(lt7911exc->regmap, 0xe05d, &data[offset], page_len);
> +               if (ret) {
> +                       dev_err(dev, "write error at page %d\n", num);
> +                       return ret;
> +               }
> +
> +               if (page_len < LT_PAGE_SIZE) {
> +                       regmap_write(lt7911exc->regmap, 0xe05f, 0x05);
> +                       regmap_write(lt7911exc->regmap, 0xe05f, 0x01);
> +                       //hardware requires delay
> +                       usleep_range(1000, 2000);
> +               }
> +
> +               regmap_write(lt7911exc->regmap, 0xe05f, 0x00);
> +               addr += LT_PAGE_SIZE;
> +       }
> +
> +       return 0;
> +}
> +
> +static int lt7911exc_write_crc(struct lt7911exc *lt7911exc, u64 addr)
> +{
> +       u8 crc[4];
> +       int ret;
> +
> +       crc[0] = lt7911exc->fw_crc & 0xff;
> +       crc[1] = (lt7911exc->fw_crc >> 8) & 0xff;
> +       crc[2] = (lt7911exc->fw_crc >> 16) & 0xff;
> +       crc[3] = (lt7911exc->fw_crc >> 24) & 0xff;
> +
> +       regmap_write(lt7911exc->regmap, 0xe05f, 0x01);
> +       regmap_write(lt7911exc->regmap, 0xe05a, (addr >> 16) & 0xff);
> +       regmap_write(lt7911exc->regmap, 0xe05b, (addr >> 8) & 0xff);
> +       regmap_write(lt7911exc->regmap, 0xe05c, addr & 0xff);
> +
> +       ret = regmap_raw_write(lt7911exc->regmap, 0xe05d, crc, 4);
> +       if (ret)
> +               return ret;
> +       regmap_write(lt7911exc->regmap, 0xe05f, 0x05);
> +       regmap_write(lt7911exc->regmap, 0xe05f, 0x01);
> +       usleep_range(1000, 2000);
> +       regmap_write(lt7911exc->regmap, 0xe05f, 0x00);
> +
> +       return 0;
> +}
> +
> +static int lt7911exc_firmware_upgrade(struct lt7911exc *lt7911exc)
> +{
> +       struct device *dev = lt7911exc->dev;
> +       int ret;
> +
> +       ret = lt7911exc_prepare_firmware_data(lt7911exc);
> +       if (ret < 0)
> +               return ret;
> +
> +       dev_dbg(dev, "starting firmware upgrade, size: %zu bytes\n", lt7911exc->fw->size);
> +
> +       lt7911exc_block_erase(lt7911exc);
> +
> +       ret = lt7911exc_write_data(lt7911exc, 0);
> +       if (ret < 0) {
> +               dev_err(dev, "failed to write firmware data\n");
> +               return ret;
> +       }
> +
> +       release_firmware(lt7911exc->fw);
> +       lt7911exc->fw = NULL;
> +
> +       ret = lt7911exc_write_crc(lt7911exc, FW_SIZE - 4);
> +       if (ret < 0) {
> +               dev_err(dev, "failed to write firmware crc\n");
> +               return ret;
> +       }
> +
> +       return 0;
> +}
> +
> +static int lt7911exc_upgrade_result(struct lt7911exc *lt7911exc)
> +{
> +       struct device *dev = lt7911exc->dev;
> +       u32 read_hw_crc = 0;
> +       u8 crc_tmp[4];
> +       int ret;
> +
> +       regmap_write(lt7911exc->regmap, 0xe0ee, 0x01);
> +       regmap_write(lt7911exc->regmap, 0xe07b, 0x60);
> +       regmap_write(lt7911exc->regmap, 0xe07b, 0x40);
> +       msleep(150);
> +       ret = regmap_bulk_read(lt7911exc->regmap, 0x22, crc_tmp, 4);
> +       if (ret) {
> +               dev_err(lt7911exc->dev, "Failed to read CRC: %d\n", ret);
> +               return ret;
> +       }
> +
> +       read_hw_crc = crc_tmp[0] << 24 | crc_tmp[1] << 16 |
> +                               crc_tmp[2] << 8 | crc_tmp[3];
> +
> +       if (read_hw_crc != lt7911exc->fw_crc) {
> +               dev_err(dev, "lt7911exc firmware upgrade failed, expected CRC=0x%08x, read CRC=0x%08x\n",
> +                       lt7911exc->fw_crc, read_hw_crc);
> +               return -EIO;
> +       }
> +
> +       dev_dbg(dev, "lt7911exc firmware upgrade success, CRC=0x%08x\n", read_hw_crc);
> +       return 0;
> +}
> +
> +static void lt7911exc_pre_enable(struct drm_bridge *bridge)
> +{
> +       struct lt7911exc *lt7911exc = bridge_to_lt7911exc(bridge);
> +       int ret;
> +
> +       if (lt7911exc->enabled)
> +               return;
> +
> +       ret = lt7911exc_regulator_enable(lt7911exc);
> +       if (ret)
> +               return;
> +
> +       lt7911exc_reset(lt7911exc);
> +
> +       lt7911exc->enabled = true;
> +}
> +
> +static void lt7911exc_disable(struct drm_bridge *bridge)
> +{
> +       /* Delay after panel is disabled */
> +       msleep(20);
> +}
> +
> +static void lt7911exc_post_disable(struct drm_bridge *bridge)
> +{
> +       struct lt7911exc *lt7911exc = bridge_to_lt7911exc(bridge);
> +       int ret;
> +
> +       if (!lt7911exc->enabled)
> +               return;
> +
> +       lt7911exc->enabled = false;
> +
> +       ret = lt7911exc_regulator_disable(lt7911exc);
> +       if (ret)
> +               return;
> +
> +       gpiod_set_value_cansleep(lt7911exc->reset_gpio, 0);
> +}
> +
> +static int lt7911exc_attach(struct drm_bridge *bridge,
> +                           struct drm_encoder *encoder,
> +                           enum drm_bridge_attach_flags flags)
> +{
> +       struct lt7911exc *lt7911exc = bridge_to_lt7911exc(bridge);
> +
> +       return drm_bridge_attach(lt7911exc->bridge.encoder, lt7911exc->panel_bridge,
> +                                &lt7911exc->bridge, flags);
> +}
> +
> +static const struct drm_bridge_funcs lt7911exc_bridge_funcs = {
> +       .pre_enable = lt7911exc_pre_enable,
> +       .disable = lt7911exc_disable,
> +       .post_disable = lt7911exc_post_disable,
> +       .attach = lt7911exc_attach,
> +};
> +
> +static int lt7911exc_probe(struct i2c_client *client)
> +{
> +       struct device *dev = &client->dev;
> +       struct lt7911exc *lt7911exc;
> +       struct drm_bridge *panel_bridge;
> +       bool fw_updated = false;
> +       int ret;
> +
> +       if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
> +               dev_err(dev, "device doesn't support I2C\n");
> +               return -ENODEV;
> +       }
> +
> +       lt7911exc = devm_drm_bridge_alloc(dev, struct lt7911exc, bridge,
> +                                         &lt7911exc_bridge_funcs);
> +       if (IS_ERR(lt7911exc))
> +               return PTR_ERR(lt7911exc);
> +
> +       panel_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 0);
> +       if (IS_ERR(panel_bridge))
> +               return PTR_ERR(panel_bridge);
> +
> +       lt7911exc->panel_bridge = panel_bridge;
> +       lt7911exc->client = client;
> +       lt7911exc->dev = dev;
> +       i2c_set_clientdata(client, lt7911exc);
> +       mutex_init(&lt7911exc->ocm_lock);

devm_mutex_init()

> +
> +       lt7911exc->regmap = devm_regmap_init_i2c(client, &lt7911exc_regmap_config);
> +       if (IS_ERR(lt7911exc->regmap)) {
> +               dev_err(dev, "regmap i2c init failed\n");
> +               return PTR_ERR(lt7911exc->regmap);
> +       }
> +
> +       ret = lt7911exc_parse_dt(lt7911exc);
> +       if (ret)
> +               return ret;
> +
> +       ret = lt7911exc_regulator_enable(lt7911exc);
> +       if (ret)
> +               return ret;
> +
> +       lt7911exc_reset(lt7911exc);
> +       lt7911exc->enabled = true;
> +       lt7911exc_lock(lt7911exc);
> +
> +retry:
> +       lt7911exc->fw_version = lt7911exc_read_version(lt7911exc);
> +       if (lt7911exc->fw_version < 0) {
> +               dev_err(dev, "failed to read FW version\n");
> +               lt7911exc_unlock(lt7911exc);
> +               goto err_disable_regulators;
> +
> +       } else if (lt7911exc->fw_version == 0) {
> +               if (!fw_updated) {
> +                       fw_updated = true;
> +                       ret = lt7911exc_firmware_upgrade(lt7911exc);
> +                       if (ret < 0) {
> +                               lt7911exc_unlock(lt7911exc);
> +                               goto err_disable_regulators;
> +                       }
> +
> +                       lt7911exc_reset(lt7911exc);
> +
> +                       ret = lt7911exc_upgrade_result(lt7911exc);
> +                       if (ret < 0) {
> +                               lt7911exc_unlock(lt7911exc);
> +                               goto err_disable_regulators;
> +                       }
> +
> +                       goto retry;
> +
> +               } else {
> +                       dev_err(dev, "fw version 0x%04x, update failed\n", lt7911exc->fw_version);
> +                       ret = -EOPNOTSUPP;
> +                       lt7911exc_unlock(lt7911exc);
> +                       goto err_disable_regulators;
> +               }
> +       }
> +
> +       lt7911exc_unlock(lt7911exc);
> +
> +       lt7911exc->bridge.type = DRM_MODE_CONNECTOR_DSI;

So, this is the DSI host. Where do you register one? Where do you
populate the DT entries (if there is a panel attached to this bridge
it will be a child node).

> +       lt7911exc->bridge.of_node = dev->of_node;
> +       drm_bridge_add(&lt7911exc->bridge);

devm_drm_bridge_add().

> +
> +       return 0;
> +
> +err_disable_regulators:
> +       regulator_bulk_disable(ARRAY_SIZE(lt7911exc->supplies), lt7911exc->supplies);
> +       if (lt7911exc->fw) {
> +               release_firmware(lt7911exc->fw);
> +               lt7911exc->fw = NULL;
> +       }
> +
> +       return ret;
> +}
> +
> +static void lt7911exc_remove(struct i2c_client *client)
> +{
> +       struct lt7911exc *lt7911exc = i2c_get_clientdata(client);
> +
> +       drm_bridge_remove(&lt7911exc->bridge);
> +       mutex_destroy(&lt7911exc->ocm_lock);
> +}
> +
> +static const struct i2c_device_id lt7911exc_i2c_table[] = {
> +       {"lontium, lt7911exc", 0},
> +       { /* sentinel */ }
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, lt7911exc_i2c_table);
> +
> +static const struct of_device_id lt7911exc_devices[] = {
> +       {.compatible = "lontium,lt7911exc",},
> +       {}
> +};
> +MODULE_DEVICE_TABLE(of, lt7911exc_devices);
> +
> +static struct i2c_driver lt7911exc_driver = {
> +       .id_table       = lt7911exc_i2c_table,
> +       .probe          = lt7911exc_probe,
> +       .remove         = lt7911exc_remove,
> +       .driver         = {
> +               .name   = "lt7911exc",
> +               .of_match_table = lt7911exc_devices,
> +       },
> +};
> +module_i2c_driver(lt7911exc_driver);
> +
> +MODULE_AUTHOR("SunYun Yang <syyang@lontium.com>");
> +MODULE_DESCRIPTION("Lontium lt7911exc edp to mipi dsi bridge driver");

MIPI, DSI. It LT7911EXC or lt7911exc?

> +MODULE_LICENSE("GPL v2");
> --
> 2.34.1
>


-- 
With best wishes
Dmitry