Re: [PATCH v7 2/2] drm/bridge: Add Lontium LT9609C(EX/UXD) MIPI DSI to HDMI driver

[Krzysztof Kozlowski <krzk@kernel.org>]

On 16/07/2026 13:31, mohit.dsor@oss.qualcomm.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>
> Co-developed-by: Mohit Dsor <mohit.dsor@oss.qualcomm.com>
> Signed-off-by: Mohit Dsor <mohit.dsor@oss.qualcomm.com>
> ---
>  MAINTAINERS                              |    7 +
>  drivers/gpu/drm/bridge/Kconfig           |   18 +
>  drivers/gpu/drm/bridge/Makefile          |    1 +
>  drivers/gpu/drm/bridge/lontium-lt9611c.c | 1293 ++++++++++++++++++++++++++++++
>  4 files changed, 1319 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 6dea93a41962..30be2eaf2bec 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -15184,6 +15184,13 @@ S:	Maintained
>  F:	Documentation/devicetree/bindings/display/bridge/lontium,lt8912b.yaml
>  F:	drivers/gpu/drm/bridge/lontium-lt8912b.c
>  
> +LONTIUM LT9611C MIPI DSI TO HDMI BRIDGE
> +M:	Sunyun Yang <syyang@lontium.com>
> +M:	Mohit Dsor <mohit.dsor@oss.qualcomm.com>
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/display/bridge/lontium,lt9611.yaml
> +F:	drivers/gpu/drm/bridge/lontium-lt9611c.c
> +
>  LOONGARCH
>  M:	Huacai Chen <chenhuacai@kernel.org>
>  R:	WANG Xuerui <kernel@xen0n.name>
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index 4a57d49b4c6d..b8959b8e2ad0 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.

Please wrap the code to appropriate limits.

...

> +
> +static void lt9611c_reset(struct lt9611c *lt9611c)
> +{
> +	gpiod_set_value_cansleep(lt9611c->reset_gpio, 1);
> +	usleep_range(10000, 12000);
> +
> +	gpiod_set_value_cansleep(lt9611c->reset_gpio, 0);
> +	msleep(400);
> +
> +	dev_dbg(lt9611c->dev, "lt9611c reset");

Same comment as before.

> +}
> +

> +static int lt9611c_upgrade_result(struct lt9611c *lt9611c, u8 fw_crc)
> +{
> +	struct device *dev = lt9611c->dev;
> +	unsigned int crc_result;
> +
> +	regmap_write(lt9611c->regmap, 0xe0ee, 0x01);
> +	regmap_read(lt9611c->regmap, 0xe021, &crc_result);
> +
> +	if (crc_result != fw_crc) {
> +		dev_err(dev, "lt9611c fw upgrade failed, expected crc=0x%02x, read crc=0x%02x\n",
> +			fw_crc, crc_result);
> +		return -1;
> +	}
> +
> +	dev_dbg(dev, "lt9611c firmware upgrade success, crc=0x%02x\n", crc_result);
> +	return 0;
> +}

...

> +
> +static ssize_t lt9611c_firmware_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	struct lt9611c *lt9611c = dev_get_drvdata(dev);
> +
> +	return sysfs_emit(buf, "0x%04x\n", lt9611c->fw_version);
> +}
> +
> +static DEVICE_ATTR_RW(lt9611c_firmware);

Where is this ABI documented?

> +
> +static struct attribute *lt9611c_attrs[] = {
> +	&dev_attr_lt9611c_firmware.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group lt9611c_attr_group = {
> +	.attrs = lt9611c_attrs,
> +};
> +
> +static const struct attribute_group *lt9611c_attr_groups[] = {
> +	&lt9611c_attr_group,
> +	NULL,
> +};
> +
> +static int lt9611c_probe(struct i2c_client *client)
> +{
> +	struct lt9611c *lt9611c;
> +	struct device *dev = &client->dev;
> +	bool fw_updated = false;
> +	int ret;
> +
> +	crc8_populate_msb(lt9611c_crc8_table, LT9611C_CRC_POLYNOMIAL);
> +
> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
> +		return dev_err_probe(dev, -ENODEV, "device doesn't support I2C\n");
> +
> +	lt9611c = devm_drm_bridge_alloc(dev, struct lt9611c, bridge, &lt9611c_bridge_funcs);
> +	if (IS_ERR(lt9611c))
> +		return dev_err_probe(dev, PTR_ERR(lt9611c), "drm bridge alloc failed.\n");
> +
> +	lt9611c->dev = dev;
> +	lt9611c->client = client;
> +	lt9611c->chip_type = (uintptr_t)i2c_get_match_data(client);

uintptr_t is not for kernel, use unsigned long.


> +
> +	ret = devm_mutex_init(dev, &lt9611c->ocm_lock);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to init mutex\n");
> +
> +	lt9611c->regmap = devm_regmap_init_i2c(client, &lt9611c_regmap_config);
> +	if (IS_ERR(lt9611c->regmap))
> +		return dev_err_probe(dev, PTR_ERR(lt9611c->regmap), "regmap i2c init failed\n");
> +
> +	ret = lt9611c_parse_dt(dev, lt9611c);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to parse device tree\n");
> +
> +	ret = lt9611c_gpio_init(lt9611c);
> +	if (ret < 0)
> +		goto err_of_put;
> +
> +	ret = lt9611c_regulator_init(lt9611c);
> +	if (ret < 0)
> +		goto err_of_put;
> +
> +	ret = regulator_bulk_enable(ARRAY_SIZE(lt9611c->supplies), lt9611c->supplies);
> +	if (ret)
> +		goto err_of_put;
> +
> +	lt9611c_reset(lt9611c);
> +
> +	lt9611c_lock(lt9611c);
> +
> +	ret = lt9611c_read_chipid(lt9611c);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to read chip id.\n");
> +		lt9611c_unlock(lt9611c);
> +		goto err_disable_regulators;
> +	}
> +
> +retry:
> +	lt9611c->fw_version = lt9611c_read_version(lt9611c);
> +	if (lt9611c->fw_version < 0) {
> +		dev_err(dev, "failed to read fw version\n");
> +		ret = -EOPNOTSUPP;
> +		lt9611c_unlock(lt9611c);
> +		goto err_disable_regulators;
> +
> +	} else if (lt9611c->fw_version == 0) {
> +		if (!fw_updated) {
> +			fw_updated = true;
> +			ret = lt9611c_firmware_upgrade(lt9611c);
> +			if (ret < 0) {
> +				lt9611c_unlock(lt9611c);
> +				goto err_disable_regulators;
> +			}
> +
> +			goto retry;
> +
> +		} else {
> +			dev_err(dev, "fw version 0x%04x, update failed\n", lt9611c->fw_version);
> +			ret = -EOPNOTSUPP;
> +			lt9611c_unlock(lt9611c);
> +			goto err_disable_regulators;
> +		}
> +	}
> +
> +	lt9611c_unlock(lt9611c);
> +	dev_dbg(dev, "current version:0x%04x", lt9611c->fw_version);
> +
> +	INIT_WORK(&lt9611c->work, lt9611c_hpd_work);
> +
> +	ret = devm_request_threaded_irq(&client->dev, client->irq, NULL,
> +					lt9611c_irq_thread_handler,
> +					IRQF_TRIGGER_FALLING |
> +					IRQF_ONESHOT |
> +					IRQF_NO_AUTOEN,
> +					"lt9611c", lt9611c);
> +	if (ret) {
> +		dev_err(dev, "failed to request irq\n");
> +		goto err_disable_regulators;
> +	}
> +
> +	lt9611c->bridge.of_node = client->dev.of_node;
> +	lt9611c->bridge.ops = DRM_BRIDGE_OP_DETECT |
> +			DRM_BRIDGE_OP_EDID |
> +			DRM_BRIDGE_OP_HPD |
> +			DRM_BRIDGE_OP_HDMI |
> +			DRM_BRIDGE_OP_HDMI_AUDIO;
> +	lt9611c->bridge.type = DRM_MODE_CONNECTOR_HDMIA;
> +
> +	lt9611c->bridge.vendor = "Lontium";
> +	lt9611c->bridge.product = "LT9611C";
> +
> +	lt9611c->bridge.hdmi_audio_dev = dev;
> +	lt9611c->bridge.hdmi_audio_max_i2s_playback_channels = 8;
> +	lt9611c->bridge.hdmi_audio_dai_port = 2;
> +
> +	devm_drm_bridge_add(dev, &lt9611c->bridge);
> +
> +	/* Attach primary DSI */
> +	lt9611c->dsi0 = lt9611c_attach_dsi(lt9611c, lt9611c->dsi0_node);
> +	if (IS_ERR(lt9611c->dsi0)) {
> +		ret = PTR_ERR(lt9611c->dsi0);
> +		goto err_remove_bridge;
> +	}
> +
> +	/* Attach secondary DSI, if specified */
> +	if (lt9611c->dsi1_node) {
> +		lt9611c->dsi1 = lt9611c_attach_dsi(lt9611c, lt9611c->dsi1_node);
> +		if (IS_ERR(lt9611c->dsi1)) {
> +			ret = PTR_ERR(lt9611c->dsi1);
> +			goto err_remove_bridge;
> +		}
> +	}
> +
> +	lt9611c->hdmi_connected = false;
> +	i2c_set_clientdata(client, lt9611c);
> +	enable_irq(client->irq);
> +
> +	lt9611c_reset(lt9611c);
> +	return 0;
> +
> +err_remove_bridge:
> +	cancel_work_sync(&lt9611c->work);
> +
> +err_disable_regulators:
> +	regulator_bulk_disable(ARRAY_SIZE(lt9611c->supplies), lt9611c->supplies);
> +
> +err_of_put:
> +	of_node_put(lt9611c->dsi1_node);
> +	of_node_put(lt9611c->dsi0_node);
> +
> +	return ret;
> +}
> +
> +static void lt9611c_remove(struct i2c_client *client)
> +{
> +	struct lt9611c *lt9611c = i2c_get_clientdata(client);
> +
> +	cancel_work_sync(&lt9611c->work);
> +	regulator_bulk_disable(ARRAY_SIZE(lt9611c->supplies), lt9611c->supplies);
> +	of_node_put(lt9611c->dsi1_node);
> +	of_node_put(lt9611c->dsi0_node);
> +}
> +
> +static int lt9611c_bridge_suspend(struct device *dev)
> +{
> +	struct lt9611c *lt9611c = dev_get_drvdata(dev);
> +	int ret;
> +
> +	dev_dbg(lt9611c->dev, "suspend\n");

Same comments.


This does not look like useful printk message. Drivers should be silent
on success:
https://elixir.bootlin.com/linux/v6.15-rc7/source/Documentation/process/coding-style.rst#L913
https://elixir.bootlin.com/linux/v6.15-rc7/source/Documentation/process/debugging/driver_development_debugging_guide.rst#L79

Best regards,
Krzysztof