The tmds181 and sn65dp159 are "retimers" and hence can be considered
HDMI-to-HDMI bridges. Typical usage is to convert the output of an
FPGA into a valid HDMI signal, and it will typically be inserted
between an encoder and hdmi-connector.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
---

 drivers/gpu/drm/bridge/Kconfig      |  11 +
 drivers/gpu/drm/bridge/Makefile     |   1 +
 drivers/gpu/drm/bridge/ti-tmds181.c | 512 ++++++++++++++++++++++++++++
 3 files changed, 524 insertions(+)
 create mode 100644 drivers/gpu/drm/bridge/ti-tmds181.c

diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
index b9e0ca85226a..753177fc9b50 100644
--- a/drivers/gpu/drm/bridge/Kconfig
+++ b/drivers/gpu/drm/bridge/Kconfig
@@ -430,6 +430,17 @@ config DRM_TI_SN65DSI86
 	help
 	  Texas Instruments SN65DSI86 DSI to eDP Bridge driver
 
+config DRM_TI_TMDS181
+        tristate "TI TMDS181 and SN65DP159 HDMI retimer bridge driver"
+	depends on OF
+	select DRM_KMS_HELPER
+	select REGMAP_I2C
+	help
+	  Enable this to support the TI TMDS181 and SN65DP159 HDMI retimers.
+	  The SN65DP159 provides output into a cable (source) whereas the
+	  TMDS181 is meant to forward a cable signal into a PCB (sink). Either
+	  can be set up as source or sink though.
+
 config DRM_TI_TPD12S015
 	tristate "TI TPD12S015 HDMI level shifter and ESD protection"
 	depends on OF
diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
index 245e8a27e3fc..f4b5089e903c 100644
--- a/drivers/gpu/drm/bridge/Makefile
+++ b/drivers/gpu/drm/bridge/Makefile
@@ -39,6 +39,7 @@ obj-$(CONFIG_DRM_TI_SN65DSI83) += ti-sn65dsi83.o
 obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o
 obj-$(CONFIG_DRM_TI_TDP158) += ti-tdp158.o
 obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
+obj-$(CONFIG_DRM_TI_TMDS181) += ti-tmds181.o
 obj-$(CONFIG_DRM_TI_TPD12S015) += ti-tpd12s015.o
 obj-$(CONFIG_DRM_NWL_MIPI_DSI) += nwl-dsi.o
 obj-$(CONFIG_DRM_ITE_IT66121) += ite-it66121.o
diff --git a/drivers/gpu/drm/bridge/ti-tmds181.c b/drivers/gpu/drm/bridge/ti-tmds181.c
new file mode 100644
index 000000000000..6fbbc13ddc10
--- /dev/null
+++ b/drivers/gpu/drm/bridge/ti-tmds181.c
@@ -0,0 +1,512 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * TI tmds181 and sn65dp159 HDMI redriver and retimer chips
+ *
+ * Copyright (C) 2018 - 2025 Topic Embedded Products <www.topic.nl>
+ *
+ * based on code
+ * Copyright (C) 2007 Hans Verkuil
+ * Copyright (C) 2016, 2017 Leon Woestenberg <leon@sidebranch.com>
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/i2c.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/gpio/consumer.h>
+#include <linux/delay.h>
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_bridge.h>
+#include <drm/drm_crtc.h>
+#include <drm/drm_print.h>
+#include <drm/drm_probe_helper.h>
+
+MODULE_DESCRIPTION("I2C device driver for DP159 and TMDS181 redriver/retimer");
+MODULE_AUTHOR("Mike Looijmans");
+MODULE_LICENSE("GPL");
+
+#define TMDS181_REG_ID		0
+#define TMDS181_REG_REV		0x8
+#define TMDS181_REG_CTRL9	0x9
+/* Registers A and B have a volatile bit, but we don't use it, so cache is ok */
+#define TMDS181_REG_CTRLA	0xA
+#define TMDS181_REG_CTRLB	0xB
+#define TMDS181_REG_CTRLC	0xC
+#define TMDS181_REG_EQUALIZER	0xD
+#define TMDS181_REG_EYESCAN	0xE
+
+enum tmds181_chip {
+	tmds181,
+	dp159,
+};
+
+struct tmds181_data {
+	struct i2c_client *client;
+	struct regmap *regmap;
+	struct drm_bridge *next_bridge;
+	struct drm_bridge bridge;
+	enum tmds181_chip chip;
+};
+
+static inline struct tmds181_data *
+drm_bridge_to_tmds181_data(struct drm_bridge *bridge)
+{
+	return container_of(bridge, struct tmds181_data, bridge);
+}
+
+/* Set "apply" bit in control register after making changes */
+static int tmds181_apply_changes(struct tmds181_data *data)
+{
+	return regmap_write_bits(data->regmap,
+		TMDS181_REG_CTRLA, BIT(2), BIT(2));
+}
+
+static int tmds181_attach(struct drm_bridge *bridge, struct drm_encoder *encoder,
+			  enum drm_bridge_attach_flags flags)
+{
+	struct tmds181_data *data = drm_bridge_to_tmds181_data(bridge);
+
+	return drm_bridge_attach(encoder, data->next_bridge, bridge, flags);
+}
+
+static enum drm_mode_status
+tmds181_mode_valid(struct drm_bridge *bridge, const struct drm_display_info *info,
+		   const struct drm_display_mode *mode)
+{
+	/* Clock limits: clk between 25 and 350 MHz, clk is 1/10 of bit clock */
+	if (mode->clock < 25000)
+		return MODE_CLOCK_LOW;
+
+	/* The actual HDMI clock (if provided) cannot exceed 350MHz */
+	if (mode->crtc_clock > 350000)
+		return MODE_CLOCK_HIGH;
+
+	/*
+	 * When in 4k mode, the clock is 1/40th of the bitrate. The limit is
+	 * then the data rate of 6Gbps, which would use a 600MHz pixel clock.
+	 */
+	if (mode->clock > 600000)
+		return MODE_CLOCK_HIGH;
+
+	return MODE_OK;
+}
+
+static void tmds181_enable(struct drm_bridge *bridge)
+{
+	struct tmds181_data *data = drm_bridge_to_tmds181_data(bridge);
+
+	/* Clear the PD_EN bit */
+	regmap_update_bits(data->regmap, TMDS181_REG_CTRL9, BIT(3), 0);
+}
+
+static void tmds181_disable(struct drm_bridge *bridge)
+{
+	struct tmds181_data *data = drm_bridge_to_tmds181_data(bridge);
+
+	/* Set the PD_EN bit */
+	regmap_update_bits(data->regmap, TMDS181_REG_CTRL9, BIT(3), BIT(3));
+}
+
+static const struct drm_bridge_funcs tmds181_bridge_funcs = {
+	.attach		= tmds181_attach,
+	.mode_valid	= tmds181_mode_valid,
+	.enable		= tmds181_enable,
+	.disable	= tmds181_disable,
+};
+
+static const char * const tmds181_modes[] = {
+	"redriver",
+	"auto1",
+	"auto2",
+	"retimer",
+};
+
+static ssize_t mode_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct tmds181_data *data = dev_get_drvdata(dev);
+	const char *equalizer;
+	u32 val;
+	int ret;
+
+	ret = regmap_read(data->regmap, TMDS181_REG_CTRLA, &val);
+	if (ret < 0)
+		return ret;
+
+	if (val & BIT(4)) {
+		if (val & BIT(5))
+			equalizer = "eq-adaptive";
+		else
+			equalizer = "eq-fixed";
+	} else {
+		equalizer = "eq-disabled";
+	}
+
+	return scnprintf(buf, PAGE_SIZE, "%6s %s %s\n",
+			(val & BIT(7)) ? "sink" : "source",
+			tmds181_modes[val & 0x03],
+			equalizer);
+}
+
+static ssize_t mode_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct tmds181_data *data = dev_get_drvdata(dev);
+	u32 val;
+	int ret;
+	int i;
+
+	/* Strip trailing newline(s) for being user friendly */
+	while (len && buf[len] == '\n')
+		--len;
+
+	/* Need at least 4 actual characters */
+	if (len < 4)
+		return -EINVAL;
+
+	ret = regmap_read(data->regmap, TMDS181_REG_CTRLA, &val);
+	if (ret < 0)
+		return ret;
+
+	for (i = 0; i < ARRAY_SIZE(tmds181_modes); ++i) {
+		if (strncmp(tmds181_modes[i], buf, len) == 0) {
+			val &= ~0x03;
+			val |= i;
+			break;
+		}
+	}
+
+	if (strncmp("sink", buf, len) == 0)
+		val |= BIT(7);
+
+	if (strncmp("source", buf, len) == 0)
+		val &= ~BIT(7);
+
+	if (strncmp("eq-", buf, 3) == 0) {
+		switch (buf[3]) {
+		case 'a': /* adaptive */
+			val |= BIT(4) | BIT(5);
+			break;
+		case 'f': /* fixed */
+			val |= BIT(4);
+			val &= ~BIT(5);
+			break;
+		case 'd': /* disable */
+			val &= ~(BIT(4) | BIT(5));
+			break;
+		}
+	}
+
+	/* Always set the "apply changes" bit */
+	val |= BIT(2);
+
+	ret = regmap_write(data->regmap, TMDS181_REG_CTRLA, val);
+	if (ret < 0)
+		return ret;
+
+	return len;
+}
+
+/* termination for HDMI TX: 0=off, 1=150..300, 3=75..150 ohms */
+static ssize_t termination_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct tmds181_data *data = dev_get_drvdata(dev);
+	u32 val;
+	int ret;
+
+	ret = regmap_read(data->regmap, TMDS181_REG_CTRLB, &val);
+	if (ret < 0)
+		return ret;
+
+	val >>= 3;
+	val &= 0x03;
+
+	return scnprintf(buf, PAGE_SIZE, "%u\n", val);
+}
+
+static ssize_t termination_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t len)
+{
+	struct tmds181_data *data = dev_get_drvdata(dev);
+	u32 val;
+	unsigned long newval;
+	int ret;
+
+	ret = regmap_read(data->regmap, TMDS181_REG_CTRLB, &val);
+	if (ret < 0)
+		return ret;
+
+	ret = kstrtoul((const char *) buf, 10, &newval);
+	if (ret)
+		return ret;
+
+	if (newval > 3)
+		return -EINVAL;
+
+	val &= ~(0x03 << 3);
+	val |= newval << 3;
+
+	ret = regmap_write(data->regmap, TMDS181_REG_CTRLB, val);
+	if (ret < 0)
+		return ret;
+
+	return len;
+}
+
+static DEVICE_ATTR_RW(mode);
+static DEVICE_ATTR_RW(termination);
+
+static struct attribute *tmds181_attrs[] = {
+	&dev_attr_mode.attr,
+	&dev_attr_termination.attr,
+	NULL,
+};
+
+static const struct attribute_group tmds181_attr_group = {
+	.attrs = tmds181_attrs,
+};
+
+static const u8 tmds181_id_tmds181[8] = "TMDS181 ";
+static const u8 tmds181_id_dp159[8]   = "DP159   ";
+
+static int tmds181_check_id(struct tmds181_data *data)
+{
+	int ret;
+	int retry;
+	u8 buffer[8];
+
+	for (retry = 0; retry < 20; ++retry) {
+		ret = regmap_bulk_read(data->regmap, TMDS181_REG_ID, buffer,
+				       sizeof(buffer));
+		if (!ret)
+			break;
+
+		/* Compensate for very long OE power-up delays due to the cap */
+		usleep_range(5000, 10000);
+	}
+
+	if (ret) {
+		dev_err(&data->client->dev, "I2C read ID failed\n");
+		return ret;
+	}
+
+	if (memcmp(buffer, tmds181_id_tmds181, sizeof(buffer)) == 0) {
+		dev_info(&data->client->dev, "Detected: TMDS181\n");
+		data->chip = tmds181;
+		return 0;
+	}
+
+	if (memcmp(buffer, tmds181_id_dp159, sizeof(buffer)) == 0) {
+		dev_info(&data->client->dev, "Detected: DP159\n");
+		data->chip = dp159;
+		return 0;
+	}
+
+	dev_err(&data->client->dev, "Unknown or wrong ID: %*pE\n", (int)sizeof(buffer), buffer);
+
+	return -ENODEV;
+}
+
+static bool tmds181_regmap_is_volatile(struct device *dev, unsigned int reg)
+{
+	switch (reg) {
+	/* IBERT result and status registers, not used yet */
+	case 0x15:
+	case 0x17 ... 0x1F:
+		return true;
+	default:
+		return false;
+	}
+}
+
+static const struct regmap_config tmds181_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.cache_type = REGCACHE_RBTREE,
+	.max_register = 0x20,
+	.volatile_reg = tmds181_regmap_is_volatile,
+};
+
+static int tmds181_probe(struct i2c_client *client)
+{
+	struct tmds181_data *data;
+	struct gpio_desc *oe_gpio;
+	int ret;
+	u32 param;
+	u8 val;
+
+	/* Check if the adapter supports the needed features */
+	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
+		return -EIO;
+
+	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->client = client;
+	i2c_set_clientdata(client, data);
+	data->regmap = devm_regmap_init_i2c(client, &tmds181_regmap_config);
+	if (IS_ERR(data->regmap))
+		return PTR_ERR(data->regmap);
+
+	/* The "OE" pin acts as a reset */
+	oe_gpio = devm_gpiod_get_optional(&client->dev, "oe", GPIOD_OUT_LOW);
+	if (IS_ERR(oe_gpio)) {
+		ret = PTR_ERR(oe_gpio);
+		if (ret != -EPROBE_DEFER)
+			dev_err(&client->dev, "failed to acquire 'oe' gpio\n");
+		return ret;
+	}
+	if (oe_gpio) {
+		/* Need at least 100us reset pulse */
+		usleep_range(100, 200);
+		gpiod_set_value_cansleep(oe_gpio, 1);
+	}
+
+	/* Reading the ID also provides enough time for the reset */
+	ret = tmds181_check_id(data);
+	if (ret)
+		return ret;
+
+	/* We take care of power control, so disable the chips PM functions */
+	/* SIG_EN=0 PD_EN=1 HPD_AUTO_PWRDWN_DISABLE=1 I2C_DR_CTL=0b11*/
+	regmap_update_bits(data->regmap, TMDS181_REG_CTRL9, 0x1f, 0x0f);
+
+	/* Apply configuration changes */
+	if (of_property_read_bool(client->dev.of_node, "source-mode"))
+		regmap_update_bits(data->regmap,
+				TMDS181_REG_CTRLA, BIT(7), 0);
+	if (of_property_read_bool(client->dev.of_node, "sink-mode"))
+		regmap_update_bits(data->regmap,
+				TMDS181_REG_CTRLA, BIT(7), BIT(7));
+	if (of_property_read_bool(client->dev.of_node, "redriver-mode"))
+		regmap_update_bits(data->regmap,
+				TMDS181_REG_CTRLA, 0x03, 0x00);
+	if (of_property_read_bool(client->dev.of_node, "retimer-mode"))
+		regmap_update_bits(data->regmap,
+				TMDS181_REG_CTRLA, 0x03, 0x03);
+	if (of_property_read_bool(client->dev.of_node, "adaptive-equalizer"))
+		regmap_update_bits(data->regmap,
+			TMDS181_REG_CTRLA, BIT(4) | BIT(5), BIT(4) | BIT(5));
+	if (of_property_read_bool(client->dev.of_node, "disable-equalizer"))
+		regmap_update_bits(data->regmap, TMDS181_REG_CTRLA, BIT(4), 0);
+
+	switch (data->chip) {
+	case dp159:
+		/*  SLEW=0b00 Mode=HDMI DDC_TRAIN_SET=1 */
+		val = BIT(0);
+		/* Default slew rate is max */
+		param = 3;
+		if (!of_property_read_u32(client->dev.of_node,
+					"slew-rate", &param)) {
+			if (param > 3) {
+				dev_err(&client->dev, "invalid slew-rate\n");
+				return -EINVAL;
+			}
+			/* Implement 0 = slow, 3 = fast slew rate */
+			val = (3 - param) << 6;
+		}
+		if (of_property_read_bool(client->dev.of_node, "dvi-mode"))
+			val |= BIT(5);
+		break;
+	default:
+		/* DDC_DR_SEL=1 DDC_TRAIN_SETDISABLE=1 */
+		val = BIT(2) | BIT(0);
+		break;
+	}
+
+	/* termination for HDMI TX: 0=off, 1=150..300, 3=75..150 ohms */
+	if (!of_property_read_u32(client->dev.of_node, "termination", &param))
+		val |= ((param & 0x3) << 3);
+
+	ret = regmap_write(data->regmap, TMDS181_REG_CTRLB, val);
+	if (ret < 0) {
+		dev_err(&client->dev, "regmap_write(B) failed\n");
+		return ret;
+	}
+
+	val = 0; /* Default for C register */
+	if (!of_property_read_u32(client->dev.of_node, "vswing-data", &param))
+		val |= (param << 5);
+	if (!of_property_read_u32(client->dev.of_node, "vswing-clk", &param))
+		val |= (param << 2);
+	/* Datasheet recommends HDMI_TWPST=0b01 for HDMI compliance */
+	if (of_property_read_bool(client->dev.of_node, "enable-de-emphasis"))
+		val |= 0x01;
+	ret = regmap_write(data->regmap, TMDS181_REG_CTRLC, val);
+	if (ret < 0) {
+		dev_err(&client->dev, "regmap_write(C) failed\n");
+		return ret;
+	}
+
+	/* DIS_HDMI2_SWG: HDMI 1.x only, keep clock at full rate */
+	val = BIT(0);
+	if (!of_property_read_u32(client->dev.of_node, "eq-data", &param)) {
+		val |= (param << 3);
+		/* If defined, also force the "fixed" equalizer mode */
+		regmap_update_bits(data->regmap, TMDS181_REG_CTRLA, BIT(5), 0);
+	}
+	if (!of_property_read_u32(client->dev.of_node, "eq-clk", &param)) {
+		val |= (param << 1);
+		regmap_update_bits(data->regmap, TMDS181_REG_CTRLA, BIT(5), 0);
+	}
+	ret = regmap_write(data->regmap, TMDS181_REG_EQUALIZER, val);
+	if (ret < 0) {
+		dev_err(&client->dev, "regmap_write(EQUALIZER) failed\n");
+		return ret;
+	}
+
+	ret = tmds181_apply_changes(data);
+	if (ret < 0) {
+		dev_err(&client->dev, "tmds181_apply_changes failed\n");
+		return ret;
+	}
+
+	ret = sysfs_create_group(&client->dev.kobj, &tmds181_attr_group);
+	if (ret)
+		dev_err(&client->dev, "sysfs_create_group error: %d\n", ret);
+
+	/* Find next bridge in chain */
+	data->next_bridge = devm_drm_of_get_bridge(&client->dev, client->dev.of_node, 1, 0);
+	if (IS_ERR(data->next_bridge))
+		return dev_err_probe(&client->dev, PTR_ERR(data->next_bridge),
+				     "Failed to find next bridge\n");
+
+	/* Register the bridge. */
+	data->bridge.funcs = &tmds181_bridge_funcs;
+	data->bridge.of_node = client->dev.of_node;
+
+	return devm_drm_bridge_add(&client->dev, &data->bridge);
+}
+
+static const struct i2c_device_id tmds181_id[] = {
+	{ "tmds181", tmds181 },
+	{ "sn65dp159", dp159 },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, tmds181_id);
+
+#if IS_ENABLED(CONFIG_OF)
+static const struct of_device_id tmds181_of_match[] = {
+	{ .compatible = "ti,tmds181", },
+	{ .compatible = "ti,sn65dp159", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, tmds181_of_match);
+#endif
+
+static struct i2c_driver tmds181_driver = {
+	.driver = {
+		.owner = THIS_MODULE,
+		.name	= "tmds181",
+		.of_match_table = of_match_ptr(tmds181_of_match),
+	},
+	.probe		= tmds181_probe,
+	.id_table	= tmds181_id,
+};
+
+module_i2c_driver(tmds181_driver);
-- 
2.43.0


Met vriendelijke groet / kind regards,

Mike Looijmans
System Expert


TOPIC Embedded Products B.V.
Materiaalweg 4, 5681 RJ Best
The Netherlands

T: +31 (0) 499 33 69 69
E: mike.looijmans@topic.nl
W: www.topic.nl

Please consider the environment before printing this e-mail

On Tue, Aug 12, 2025 at 04:51:35PM +0200, Mike Looijmans wrote:
> The tmds181 and sn65dp159 are "retimers" and hence can be considered
> HDMI-to-HDMI bridges. Typical usage is to convert the output of an
> FPGA into a valid HDMI signal, and it will typically be inserted
> between an encoder and hdmi-connector.
> 
> Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
> ---
> 
>  drivers/gpu/drm/bridge/Kconfig      |  11 +
>  drivers/gpu/drm/bridge/Makefile     |   1 +
>  drivers/gpu/drm/bridge/ti-tmds181.c | 512 ++++++++++++++++++++++++++++
>  3 files changed, 524 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/ti-tmds181.c
> 
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index b9e0ca85226a..753177fc9b50 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -430,6 +430,17 @@ config DRM_TI_SN65DSI86
>  	help
>  	  Texas Instruments SN65DSI86 DSI to eDP Bridge driver
>  
> +config DRM_TI_TMDS181
> +        tristate "TI TMDS181 and SN65DP159 HDMI retimer bridge driver"
> +	depends on OF
> +	select DRM_KMS_HELPER
> +	select REGMAP_I2C
> +	help
> +	  Enable this to support the TI TMDS181 and SN65DP159 HDMI retimers.
> +	  The SN65DP159 provides output into a cable (source) whereas the
> +	  TMDS181 is meant to forward a cable signal into a PCB (sink). Either
> +	  can be set up as source or sink though.
> +
>  config DRM_TI_TPD12S015
>  	tristate "TI TPD12S015 HDMI level shifter and ESD protection"
>  	depends on OF
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index 245e8a27e3fc..f4b5089e903c 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -39,6 +39,7 @@ obj-$(CONFIG_DRM_TI_SN65DSI83) += ti-sn65dsi83.o
>  obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o
>  obj-$(CONFIG_DRM_TI_TDP158) += ti-tdp158.o
>  obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
> +obj-$(CONFIG_DRM_TI_TMDS181) += ti-tmds181.o
>  obj-$(CONFIG_DRM_TI_TPD12S015) += ti-tpd12s015.o
>  obj-$(CONFIG_DRM_NWL_MIPI_DSI) += nwl-dsi.o
>  obj-$(CONFIG_DRM_ITE_IT66121) += ite-it66121.o
> diff --git a/drivers/gpu/drm/bridge/ti-tmds181.c b/drivers/gpu/drm/bridge/ti-tmds181.c
> new file mode 100644
> index 000000000000..6fbbc13ddc10
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/ti-tmds181.c
> @@ -0,0 +1,512 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * TI tmds181 and sn65dp159 HDMI redriver and retimer chips
> + *
> + * Copyright (C) 2018 - 2025 Topic Embedded Products <www.topic.nl>
> + *
> + * based on code
> + * Copyright (C) 2007 Hans Verkuil
> + * Copyright (C) 2016, 2017 Leon Woestenberg <leon@sidebranch.com>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/i2c.h>
> +#include <linux/slab.h>
> +#include <linux/of.h>
> +#include <linux/regmap.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/delay.h>
> +
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_bridge.h>
> +#include <drm/drm_crtc.h>
> +#include <drm/drm_print.h>
> +#include <drm/drm_probe_helper.h>
> +
> +MODULE_DESCRIPTION("I2C device driver for DP159 and TMDS181 redriver/retimer");
> +MODULE_AUTHOR("Mike Looijmans");
> +MODULE_LICENSE("GPL");
> +
> +#define TMDS181_REG_ID		0
> +#define TMDS181_REG_REV		0x8
> +#define TMDS181_REG_CTRL9	0x9
> +/* Registers A and B have a volatile bit, but we don't use it, so cache is ok */
> +#define TMDS181_REG_CTRLA	0xA
> +#define TMDS181_REG_CTRLB	0xB
> +#define TMDS181_REG_CTRLC	0xC
> +#define TMDS181_REG_EQUALIZER	0xD
> +#define TMDS181_REG_EYESCAN	0xE

Usually it's recommended to use lowercase hex.

> +
> +enum tmds181_chip {
> +	tmds181,
> +	dp159,
> +};
> +
> +struct tmds181_data {
> +	struct i2c_client *client;
> +	struct regmap *regmap;
> +	struct drm_bridge *next_bridge;
> +	struct drm_bridge bridge;
> +	enum tmds181_chip chip;
> +};
> +

[...]

> +
> +static const char * const tmds181_modes[] = {
> +	"redriver",
> +	"auto1",
> +	"auto2",
> +	"retimer",
> +};
> +
> +static ssize_t mode_show(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct tmds181_data *data = dev_get_drvdata(dev);
> +	const char *equalizer;
> +	u32 val;
> +	int ret;
> +
> +	ret = regmap_read(data->regmap, TMDS181_REG_CTRLA, &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (val & BIT(4)) {
> +		if (val & BIT(5))
> +			equalizer = "eq-adaptive";
> +		else
> +			equalizer = "eq-fixed";
> +	} else {
> +		equalizer = "eq-disabled";
> +	}
> +
> +	return scnprintf(buf, PAGE_SIZE, "%6s %s %s\n",
> +			(val & BIT(7)) ? "sink" : "source",
> +			tmds181_modes[val & 0x03],
> +			equalizer);
> +}
> +
> +static ssize_t mode_store(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t len)
> +{
> +	struct tmds181_data *data = dev_get_drvdata(dev);
> +	u32 val;
> +	int ret;
> +	int i;
> +
> +	/* Strip trailing newline(s) for being user friendly */
> +	while (len && buf[len] == '\n')
> +		--len;
> +
> +	/* Need at least 4 actual characters */
> +	if (len < 4)
> +		return -EINVAL;
> +
> +	ret = regmap_read(data->regmap, TMDS181_REG_CTRLA, &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	for (i = 0; i < ARRAY_SIZE(tmds181_modes); ++i) {
> +		if (strncmp(tmds181_modes[i], buf, len) == 0) {
> +			val &= ~0x03;
> +			val |= i;
> +			break;
> +		}
> +	}
> +
> +	if (strncmp("sink", buf, len) == 0)
> +		val |= BIT(7);
> +
> +	if (strncmp("source", buf, len) == 0)
> +		val &= ~BIT(7);
> +
> +	if (strncmp("eq-", buf, 3) == 0) {
> +		switch (buf[3]) {
> +		case 'a': /* adaptive */
> +			val |= BIT(4) | BIT(5);
> +			break;
> +		case 'f': /* fixed */
> +			val |= BIT(4);
> +			val &= ~BIT(5);
> +			break;
> +		case 'd': /* disable */
> +			val &= ~(BIT(4) | BIT(5));
> +			break;
> +		}
> +	}
> +
> +	/* Always set the "apply changes" bit */
> +	val |= BIT(2);
> +
> +	ret = regmap_write(data->regmap, TMDS181_REG_CTRLA, val);
> +	if (ret < 0)
> +		return ret;
> +
> +	return len;
> +}
> +
> +/* termination for HDMI TX: 0=off, 1=150..300, 3=75..150 ohms */
> +static ssize_t termination_show(struct device *dev,
> +		struct device_attribute *attr, char *buf)
> +{
> +	struct tmds181_data *data = dev_get_drvdata(dev);
> +	u32 val;
> +	int ret;
> +
> +	ret = regmap_read(data->regmap, TMDS181_REG_CTRLB, &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	val >>= 3;
> +	val &= 0x03;
> +
> +	return scnprintf(buf, PAGE_SIZE, "%u\n", val);
> +}
> +
> +static ssize_t termination_store(struct device *dev,
> +		struct device_attribute *attr, const char *buf, size_t len)
> +{
> +	struct tmds181_data *data = dev_get_drvdata(dev);
> +	u32 val;
> +	unsigned long newval;
> +	int ret;
> +
> +	ret = regmap_read(data->regmap, TMDS181_REG_CTRLB, &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = kstrtoul((const char *) buf, 10, &newval);
> +	if (ret)
> +		return ret;
> +
> +	if (newval > 3)
> +		return -EINVAL;
> +
> +	val &= ~(0x03 << 3);
> +	val |= newval << 3;
> +
> +	ret = regmap_write(data->regmap, TMDS181_REG_CTRLB, val);
> +	if (ret < 0)
> +		return ret;
> +
> +	return len;
> +}
> +
> +static DEVICE_ATTR_RW(mode);
> +static DEVICE_ATTR_RW(termination);

Undocumented ABI. Why are they configured at runtime rather than through
the DT / fwnode?

> +
> +static struct attribute *tmds181_attrs[] = {
> +	&dev_attr_mode.attr,
> +	&dev_attr_termination.attr,
> +	NULL,
> +};
> +
> +static const struct attribute_group tmds181_attr_group = {
> +	.attrs = tmds181_attrs,
> +};
> +
> +static const u8 tmds181_id_tmds181[8] = "TMDS181 ";
> +static const u8 tmds181_id_dp159[8]   = "DP159   ";
> +
> +static int tmds181_check_id(struct tmds181_data *data)
> +{
> +	int ret;
> +	int retry;
> +	u8 buffer[8];
> +
> +	for (retry = 0; retry < 20; ++retry) {
> +		ret = regmap_bulk_read(data->regmap, TMDS181_REG_ID, buffer,
> +				       sizeof(buffer));
> +		if (!ret)
> +			break;
> +
> +		/* Compensate for very long OE power-up delays due to the cap */
> +		usleep_range(5000, 10000);
> +	}
> +
> +	if (ret) {
> +		dev_err(&data->client->dev, "I2C read ID failed\n");
> +		return ret;
> +	}
> +
> +	if (memcmp(buffer, tmds181_id_tmds181, sizeof(buffer)) == 0) {
> +		dev_info(&data->client->dev, "Detected: TMDS181\n");
> +		data->chip = tmds181;
> +		return 0;
> +	}
> +
> +	if (memcmp(buffer, tmds181_id_dp159, sizeof(buffer)) == 0) {
> +		dev_info(&data->client->dev, "Detected: DP159\n");
> +		data->chip = dp159;
> +		return 0;
> +	}
> +
> +	dev_err(&data->client->dev, "Unknown or wrong ID: %*pE\n", (int)sizeof(buffer), buffer);
> +
> +	return -ENODEV;
> +}
> +
> +static bool tmds181_regmap_is_volatile(struct device *dev, unsigned int reg)
> +{
> +	switch (reg) {
> +	/* IBERT result and status registers, not used yet */
> +	case 0x15:
> +	case 0x17 ... 0x1F:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +static const struct regmap_config tmds181_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.cache_type = REGCACHE_RBTREE,
> +	.max_register = 0x20,
> +	.volatile_reg = tmds181_regmap_is_volatile,
> +};
> +
> +static int tmds181_probe(struct i2c_client *client)
> +{
> +	struct tmds181_data *data;
> +	struct gpio_desc *oe_gpio;
> +	int ret;
> +	u32 param;
> +	u8 val;
> +
> +	/* Check if the adapter supports the needed features */
> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA))
> +		return -EIO;
> +
> +	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	data->client = client;
> +	i2c_set_clientdata(client, data);
> +	data->regmap = devm_regmap_init_i2c(client, &tmds181_regmap_config);
> +	if (IS_ERR(data->regmap))
> +		return PTR_ERR(data->regmap);
> +
> +	/* The "OE" pin acts as a reset */
> +	oe_gpio = devm_gpiod_get_optional(&client->dev, "oe", GPIOD_OUT_LOW);
> +	if (IS_ERR(oe_gpio)) {
> +		ret = PTR_ERR(oe_gpio);
> +		if (ret != -EPROBE_DEFER)
> +			dev_err(&client->dev, "failed to acquire 'oe' gpio\n");
> +		return ret;
> +	}
> +	if (oe_gpio) {
> +		/* Need at least 100us reset pulse */
> +		usleep_range(100, 200);
> +		gpiod_set_value_cansleep(oe_gpio, 1);
> +	}
> +
> +	/* Reading the ID also provides enough time for the reset */
> +	ret = tmds181_check_id(data);
> +	if (ret)
> +		return ret;
> +
> +	/* We take care of power control, so disable the chips PM functions */
> +	/* SIG_EN=0 PD_EN=1 HPD_AUTO_PWRDWN_DISABLE=1 I2C_DR_CTL=0b11*/
> +	regmap_update_bits(data->regmap, TMDS181_REG_CTRL9, 0x1f, 0x0f);
> +
> +	/* Apply configuration changes */
> +	if (of_property_read_bool(client->dev.of_node, "source-mode"))

Undocumented DT properties. Please document them in DT bindings.

> +		regmap_update_bits(data->regmap,
> +				TMDS181_REG_CTRLA, BIT(7), 0);
> +	if (of_property_read_bool(client->dev.of_node, "sink-mode"))
> +		regmap_update_bits(data->regmap,
> +				TMDS181_REG_CTRLA, BIT(7), BIT(7));
> +	if (of_property_read_bool(client->dev.of_node, "redriver-mode"))
> +		regmap_update_bits(data->regmap,
> +				TMDS181_REG_CTRLA, 0x03, 0x00);
> +	if (of_property_read_bool(client->dev.of_node, "retimer-mode"))
> +		regmap_update_bits(data->regmap,
> +				TMDS181_REG_CTRLA, 0x03, 0x03);
> +	if (of_property_read_bool(client->dev.of_node, "adaptive-equalizer"))
> +		regmap_update_bits(data->regmap,
> +			TMDS181_REG_CTRLA, BIT(4) | BIT(5), BIT(4) | BIT(5));
> +	if (of_property_read_bool(client->dev.of_node, "disable-equalizer"))
> +		regmap_update_bits(data->regmap, TMDS181_REG_CTRLA, BIT(4), 0);
> +
> +	switch (data->chip) {
> +	case dp159:
> +		/*  SLEW=0b00 Mode=HDMI DDC_TRAIN_SET=1 */
> +		val = BIT(0);
> +		/* Default slew rate is max */
> +		param = 3;
> +		if (!of_property_read_u32(client->dev.of_node,
> +					"slew-rate", &param)) {
> +			if (param > 3) {
> +				dev_err(&client->dev, "invalid slew-rate\n");
> +				return -EINVAL;
> +			}
> +			/* Implement 0 = slow, 3 = fast slew rate */
> +			val = (3 - param) << 6;
> +		}
> +		if (of_property_read_bool(client->dev.of_node, "dvi-mode"))
> +			val |= BIT(5);
> +		break;
> +	default:
> +		/* DDC_DR_SEL=1 DDC_TRAIN_SETDISABLE=1 */
> +		val = BIT(2) | BIT(0);
> +		break;
> +	}
> +
> +	/* termination for HDMI TX: 0=off, 1=150..300, 3=75..150 ohms */
> +	if (!of_property_read_u32(client->dev.of_node, "termination", &param))
> +		val |= ((param & 0x3) << 3);
> +
> +	ret = regmap_write(data->regmap, TMDS181_REG_CTRLB, val);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "regmap_write(B) failed\n");
> +		return ret;
> +	}
> +
> +	val = 0; /* Default for C register */
> +	if (!of_property_read_u32(client->dev.of_node, "vswing-data", &param))
> +		val |= (param << 5);
> +	if (!of_property_read_u32(client->dev.of_node, "vswing-clk", &param))
> +		val |= (param << 2);
> +	/* Datasheet recommends HDMI_TWPST=0b01 for HDMI compliance */
> +	if (of_property_read_bool(client->dev.of_node, "enable-de-emphasis"))
> +		val |= 0x01;
> +	ret = regmap_write(data->regmap, TMDS181_REG_CTRLC, val);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "regmap_write(C) failed\n");
> +		return ret;
> +	}
> +
> +	/* DIS_HDMI2_SWG: HDMI 1.x only, keep clock at full rate */
> +	val = BIT(0);
> +	if (!of_property_read_u32(client->dev.of_node, "eq-data", &param)) {
> +		val |= (param << 3);
> +		/* If defined, also force the "fixed" equalizer mode */
> +		regmap_update_bits(data->regmap, TMDS181_REG_CTRLA, BIT(5), 0);
> +	}
> +	if (!of_property_read_u32(client->dev.of_node, "eq-clk", &param)) {
> +		val |= (param << 1);
> +		regmap_update_bits(data->regmap, TMDS181_REG_CTRLA, BIT(5), 0);
> +	}
> +	ret = regmap_write(data->regmap, TMDS181_REG_EQUALIZER, val);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "regmap_write(EQUALIZER) failed\n");
> +		return ret;
> +	}
> +
> +	ret = tmds181_apply_changes(data);
> +	if (ret < 0) {
> +		dev_err(&client->dev, "tmds181_apply_changes failed\n");
> +		return ret;
> +	}
> +
> +	ret = sysfs_create_group(&client->dev.kobj, &tmds181_attr_group);
> +	if (ret)
> +		dev_err(&client->dev, "sysfs_create_group error: %d\n", ret);
> +
> +	/* Find next bridge in chain */
> +	data->next_bridge = devm_drm_of_get_bridge(&client->dev, client->dev.of_node, 1, 0);
> +	if (IS_ERR(data->next_bridge))
> +		return dev_err_probe(&client->dev, PTR_ERR(data->next_bridge),
> +				     "Failed to find next bridge\n");
> +
> +	/* Register the bridge. */
> +	data->bridge.funcs = &tmds181_bridge_funcs;
> +	data->bridge.of_node = client->dev.of_node;
> +
> +	return devm_drm_bridge_add(&client->dev, &data->bridge);
> +}
> +
> +static const struct i2c_device_id tmds181_id[] = {
> +	{ "tmds181", tmds181 },
> +	{ "sn65dp159", dp159 },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(i2c, tmds181_id);
> +
> +#if IS_ENABLED(CONFIG_OF)
> +static const struct of_device_id tmds181_of_match[] = {
> +	{ .compatible = "ti,tmds181", },
> +	{ .compatible = "ti,sn65dp159", },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, tmds181_of_match);
> +#endif
> +
> +static struct i2c_driver tmds181_driver = {
> +	.driver = {
> +		.owner = THIS_MODULE,
> +		.name	= "tmds181",
> +		.of_match_table = of_match_ptr(tmds181_of_match),
> +	},
> +	.probe		= tmds181_probe,
> +	.id_table	= tmds181_id,
> +};
> +
> +module_i2c_driver(tmds181_driver);
> -- 
> 2.43.0
> 
> 
> Met vriendelijke groet / kind regards,
> 
> Mike Looijmans
> System Expert
> 
> 
> TOPIC Embedded Products B.V.
> Materiaalweg 4, 5681 RJ Best
> The Netherlands
> 
> T: +31 (0) 499 33 69 69
> E: mike.looijmans@topic.nl
> W: www.topic.nl
> 
> Please consider the environment before printing this e-mail

-- 
With best wishes
Dmitry

On 19-08-2025 12:26, Dmitry Baryshkov wrote:
> On Tue, Aug 12, 2025 at 04:51:35PM +0200, Mike Looijmans wrote:
>> The tmds181 and sn65dp159 are "retimers" and hence can be considered
>> HDMI-to-HDMI bridges. Typical usage is to convert the output of an
>> FPGA into a valid HDMI signal, and it will typically be inserted
>> between an encoder and hdmi-connector.
>>
>> Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
>> ---
>>
>>   drivers/gpu/drm/bridge/Kconfig      |  11 +
>>   drivers/gpu/drm/bridge/Makefile     |   1 +
>>   drivers/gpu/drm/bridge/ti-tmds181.c | 512 ++++++++++++++++++++++++++++
>>   3 files changed, 524 insertions(+)
>>   create mode 100644 drivers/gpu/drm/bridge/ti-tmds181.c
>>
>> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
>> index b9e0ca85226a..753177fc9b50 100644
>> --- a/drivers/gpu/drm/bridge/Kconfig
>> +++ b/drivers/gpu/drm/bridge/Kconfig
>> @@ -430,6 +430,17 @@ config DRM_TI_SN65DSI86
>>   	help
>>   	  Texas Instruments SN65DSI86 DSI to eDP Bridge driver
>>   
>> +config DRM_TI_TMDS181
>> +        tristate "TI TMDS181 and SN65DP159 HDMI retimer bridge driver"
>> +	depends on OF
>> +	select DRM_KMS_HELPER
>> +	select REGMAP_I2C
>> +	help
>> +	  Enable this to support the TI TMDS181 and SN65DP159 HDMI retimers.
>> +	  The SN65DP159 provides output into a cable (source) whereas the
>> +	  TMDS181 is meant to forward a cable signal into a PCB (sink). Either
>> +	  can be set up as source or sink though.
>> +
>>   config DRM_TI_TPD12S015
>>   	tristate "TI TPD12S015 HDMI level shifter and ESD protection"
>>   	depends on OF
>> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
>> index 245e8a27e3fc..f4b5089e903c 100644
>> --- a/drivers/gpu/drm/bridge/Makefile
>> +++ b/drivers/gpu/drm/bridge/Makefile
>> @@ -39,6 +39,7 @@ obj-$(CONFIG_DRM_TI_SN65DSI83) += ti-sn65dsi83.o
>>   obj-$(CONFIG_DRM_TI_SN65DSI86) += ti-sn65dsi86.o
>>   obj-$(CONFIG_DRM_TI_TDP158) += ti-tdp158.o
>>   obj-$(CONFIG_DRM_TI_TFP410) += ti-tfp410.o
>> +obj-$(CONFIG_DRM_TI_TMDS181) += ti-tmds181.o
>>   obj-$(CONFIG_DRM_TI_TPD12S015) += ti-tpd12s015.o
>>   obj-$(CONFIG_DRM_NWL_MIPI_DSI) += nwl-dsi.o
>>   obj-$(CONFIG_DRM_ITE_IT66121) += ite-it66121.o
>> diff --git a/drivers/gpu/drm/bridge/ti-tmds181.c b/drivers/gpu/drm/bridge/ti-tmds181.c
>> new file mode 100644
>> index 000000000000..6fbbc13ddc10
>> --- /dev/null
>> +++ b/drivers/gpu/drm/bridge/ti-tmds181.c
>> @@ -0,0 +1,512 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * TI tmds181 and sn65dp159 HDMI redriver and retimer chips
>> + *
>> + * Copyright (C) 2018 - 2025 Topic Embedded Products <www.topic.nl>
>> + *
>> + * based on code
>> + * Copyright (C) 2007 Hans Verkuil
>> + * Copyright (C) 2016, 2017 Leon Woestenberg <leon@sidebranch.com>
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/kernel.h>
>> +#include <linux/i2c.h>
>> +#include <linux/slab.h>
>> +#include <linux/of.h>
>> +#include <linux/regmap.h>
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/delay.h>
>> +
>> +#include <drm/drm_atomic_helper.h>
>> +#include <drm/drm_bridge.h>
>> +#include <drm/drm_crtc.h>
>> +#include <drm/drm_print.h>
>> +#include <drm/drm_probe_helper.h>
>> +
>> +MODULE_DESCRIPTION("I2C device driver for DP159 and TMDS181 redriver/retimer");
>> +MODULE_AUTHOR("Mike Looijmans");
>> +MODULE_LICENSE("GPL");
>> +
>> +#define TMDS181_REG_ID		0
>> +#define TMDS181_REG_REV		0x8
>> +#define TMDS181_REG_CTRL9	0x9
>> +/* Registers A and B have a volatile bit, but we don't use it, so cache is ok */
>> +#define TMDS181_REG_CTRLA	0xA
>> +#define TMDS181_REG_CTRLB	0xB
>> +#define TMDS181_REG_CTRLC	0xC
>> +#define TMDS181_REG_EQUALIZER	0xD
>> +#define TMDS181_REG_EYESCAN	0xE
> Usually it's recommended to use lowercase hex.

Will change in v3


>> ...
>> +	/* Apply configuration changes */
>> +	if (of_property_read_bool(client->dev.of_node, "source-mode"))
> Undocumented DT properties. Please document them in DT bindings.

Damn, this is the wrong version of the file, this looks like it's just 
v1 again. I'll post v3 ASAP.


> ...


-- 
Mike Looijmans

Hi Mike,

kernel test robot noticed the following build warnings:

[auto build test WARNING on 53e760d8949895390e256e723e7ee46618310361]

url:    https://github.com/intel-lab-lkp/linux/commits/Mike-Looijmans/dt-bindings-drm-bridge-ti-tmds181-Add-TI-TMDS181-and-SN65DP159-bindings/20250812-225413
base:   53e760d8949895390e256e723e7ee46618310361
patch link:    https://lore.kernel.org/r/20250812145256.135645-3-mike.looijmans%40topic.nl
patch subject: [PATCH 2/2] drm: bridge: Add TI tmds181 and sn65dp159 driver
config: loongarch-allyesconfig (https://download.01.org/0day-ci/archive/20250813/202508131549.DaogZRF9-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 3769ce013be2879bf0b329c14a16f5cb766f26ce)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250813/202508131549.DaogZRF9-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202508131549.DaogZRF9-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> drivers/gpu/drm/bridge/ti-tmds181.c:273:41: warning: initializer-string for character array is too long, array size is 8 but initializer has size 9 (including the null terminating character); did you mean to use the 'nonstring' attribute? [-Wunterminated-string-initialization]
     273 | static const u8 tmds181_id_tmds181[8] = "TMDS181 ";
         |                                         ^~~~~~~~~~
   drivers/gpu/drm/bridge/ti-tmds181.c:274:41: warning: initializer-string for character array is too long, array size is 8 but initializer has size 9 (including the null terminating character); did you mean to use the 'nonstring' attribute? [-Wunterminated-string-initialization]
     274 | static const u8 tmds181_id_dp159[8]   = "DP159   ";
         |                                         ^~~~~~~~~~
   2 warnings generated.


vim +/nonstring +273 drivers/gpu/drm/bridge/ti-tmds181.c

   272	
 > 273	static const u8 tmds181_id_tmds181[8] = "TMDS181 ";
   274	static const u8 tmds181_id_dp159[8]   = "DP159   ";
   275	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki