Hello Mohit,
> LT9611C(EX/UXD) is an I2C-controlled chip that Receiver signal/dual port
> mipi dsi and output hdmi, differences in hardware features:
>
> Reviewed-by: Dmitry Baryshkov <[email protected]>
> Signed-off-by: Sunyun Yang <[email protected]>
> Co-developed-by: Mohit Dsor <[email protected]>
> Signed-off-by: Mohit Dsor <[email protected]>
Looks good overall, but I have various small improvements to suggest, see
below.
Additionally, can you have a look at the issues reported by Sashiko and
reply stating whether you think they are relevant (and they should be
fixed) or not relevant (and why)?
> --- 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 && I2C
> + select CRC8
> + select FW_LOADER
> + select DRM_PANEL_BRIDGE
I don't think the code in this revision uses the DRM_PANEL_BRIDGE API.
> +++ b/drivers/gpu/drm/bridge/lontium-lt9611c.c
> @@ -0,0 +1,1283 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2026 Lontium Semiconductor, Inc.
> + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
^
Nit: both 'C' uppercase
> +#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>
Unused include?
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/unaligned.h>
> +#include <drm/drm_atomic_helper.h>
> +#include <drm/drm_bridge.h>
> +#include <drm/drm_connector.h>
> +#include <drm/drm_drv.h>
Unused include?
> +#include <drm/drm_edid.h>
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_modes.h>
> +#include <drm/drm_of.h>
Unused include?
> +#include <drm/drm_print.h>
Unused include?
> +#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 "Lontium/lt9611c_fw.bin"
> +#define LT9611C_CRC_POLYNOMIAL 0x31
> +#define LT9611C_PAGE_CONTROL 0xff
> +#define LT9611C_INFOFRAME_MAX_SIZE 32
> +#define LT9611C_CMD_HDR_SIZE 4
> +#define LT9611C_CMD_Y0_SIZE 1 /* Y0 echo byte in ACK response */
> +#define LT9611C_EDID_BUF_SIZE 32
> +
> +struct lt9611c_cmd_hdr {
> + u8 func;
> + u8 type;
> + u8 seq;
> + u8 sep;
> +};
> +
> +/* lt9611c_cmd_hdr.func values */
> +#define LT9611C_FUNC_WRITE 0x57 /* 'W' */
> +#define LT9611C_FUNC_READ 0x52 /* 'R' */
> +#define LT9611C_FUNC_ACK 0x41 /* 'A' */
> +
> +/* lt9611c_cmd_hdr.type values */
> +#define LT9611C_TYPE_MIPI 0x4d /* 'M' */
> +#define LT9611C_TYPE_LVDS 0x4c /* 'L' */
> +#define LT9611C_TYPE_HDMI 0x48 /* 'H' */
> +#define LT9611C_TYPE_AUDIO 0x41 /* 'A' */
> +#define LT9611C_TYPE_CUSTOM 0x43 /* 'C' */
> +
> +/* lt9611c_cmd_hdr.sep is always ':' */
> +#define LT9611C_CMD_SEP 0x3a /* ':' */
> +
> +struct lt9611c_cmd {
> + struct lt9611c_cmd_hdr hdr;
> + const u8 *data;
> + size_t data_len;
> +};
> +
> +struct lt9611c_rsp {
> + struct lt9611c_cmd_hdr hdr;
> + u8 *data;
> + unsigned int data_len;
> +};
> +
> +enum lt9611_chip_type {
> + CHIP_LT9611C = 0,
> + CHIP_LT9611EX,
> + CHIP_LT9611UXD,
> +};
> +
> +struct lt9611c_chip_data {
> + enum lt9611_chip_type chip_type;
> + unsigned long long max_tmds_rate;
> +};
> +
> +static const struct lt9611c_chip_data lt9611c_chip_data[] = {
> + [CHIP_LT9611C] = { CHIP_LT9611C, 340000000 },
> + [CHIP_LT9611EX] = { CHIP_LT9611EX, 340000000 },
> + [CHIP_LT9611UXD] = { CHIP_LT9611UXD, 600000000 },
> +};
> +
> +struct lt9611c {
> + struct device *dev;
> + struct i2c_client *client;
> + struct drm_bridge bridge;
> + struct regmap *regmap;
> + struct mutex mcu_lock;
> + struct work_struct work;
> + struct device_node *dsi0_node;
> + struct device_node *dsi1_node;
These two device_nodes are unused after probe finishes, so storing them for
the entire device lifetime is unnecessary. You could make
lt9611c_parse_dt() return them to lt9611c_probe(), taking care of putting
them correctly.
While that, consider using
struct device_node __free(device_node) dsi0_node = ...;
instead of
struct device_node dsi0_node;
...
dsi0_node = ...;
...
of_node_put(dsi0_node);
when applicable
> + struct mipi_dsi_device *dsi0;
> + struct mipi_dsi_device *dsi1;
And these two are never used outside of lt9611c_probe(). Make them
temporary variables in lt9611c_probe().
> + struct gpio_desc *reset_gpio;
> + struct regulator_bulk_data supplies[2];
> + int fw_version;
> + /* Chip variant: C/EX/UXD */
> + enum lt9611_chip_type chip_type;
> + unsigned long long max_tmds_rate;
Why storing a copy of these two? You can just store the 'const struct
lt9611c_chip_data *' returned by i2c_get_match_data(), which points to an
entry in the static i2c_get_match_data[], and use it to fetch the
model-specific info. As a bonus this will also be future-proof in case more
fields are added to struct lt9611c_chip_data in the future.
> +static int lt9611c_write_data(struct lt9611c *lt9611c, const struct firmware
> *fw, size_t addr)
> +{
> + struct device *dev = lt9611c->dev;
> + int ret;
> + unsigned int page = 0, num = 0, i = 0;
No need to initialize these variables, they are set before reading.
> + size_t size, index;
> + const u8 *data;
> + u8 value;
> +
> + data = fw->data;
> + size = fw->size;
> + page = DIV_ROUND_UP(size, LT_PAGE_SIZE);
'page' really holds the number of pages, please rename to 'npages' or
'pages'.
> + 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 %zu byte\n", page, size);
> +
> + for (num = 0; num < page; num++) {
Some variables (i, ret, value, maybe others?) are only used inside the
loop, move their declaration inside the loop.
> + lt9611c_data_to_sram(lt9611c);
> +
> + for (i = 0; i < LT_PAGE_SIZE; i++) {
> + index = num * LT_PAGE_SIZE + i;
> + value = (index < size) ? data[index] : 0xff;
> +
> + ret = regmap_write(lt9611c->regmap, 0xe059, value);
> + if (ret < 0) {
> + dev_err(dev, "write error at page %u, index
> %u\n", num, i);
> + return ret;
> + }
> + }
> +
> + lt9611c_wren(lt9611c);
> + lt9611c_sram_to_flash(lt9611c, addr);
> +
> + addr += LT_PAGE_SIZE;
> + }
> +
> + lt9611c_wrdi(lt9611c);
> +
> + return 0;
> +}
...
> +static int lt9611c_firmware_upgrade(struct lt9611c *lt9611c)
> +{
> + struct device *dev = lt9611c->dev;
> + const struct firmware *fw;
> + u8 *buffer;
> + size_t total_size = FW_SIZE - 1;
> + u8 fw_crc;
> + int ret;
> +
> + /* load firmware — must happen outside the mcu_lock */
Ain't this obvious? I'd remove this comment line.
> +static irqreturn_t lt9611c_irq_thread_handler(int irq, void *dev_id)
> +{
> + struct lt9611c *lt9611c = dev_id;
> + struct device *dev = lt9611c->dev;
> + int ret;
> + unsigned int irq_status;
> +
> + guard(mutex)(<9611c->mcu_lock);
> +
> + ret = regmap_read(lt9611c->regmap, 0xe084, &irq_status);
> + if (ret) {
> + dev_err(dev, "failed to read irq status: %d\n", ret);
> + return IRQ_HANDLED;
> + }
> +
> + if (!(irq_status & BIT(0)))
> + return IRQ_NONE;
> +
> + /*Clear interrupt: hardware requires two writes with delay*/
Nit: space after '/*' and before '*/'.
Same in other places in this patch.
> +static int lt9611c_regulator_init(struct lt9611c *lt9611c)
> +{
> + struct device *dev = lt9611c->dev;
> + int ret;
> +
> + lt9611c->supplies[0].supply = "vcc";
> + lt9611c->supplies[1].supply = "vdd";
> +
> + ret = devm_regulator_bulk_get(dev, 2, lt9611c->supplies);
> +
> + return ret;
Just:
return devm_regulator_bulk_get(dev, 2, lt9611c->supplies);
and remove the 'ret' variable.
> +static int lt9611c_bridge_attach(struct drm_bridge *bridge,
> + struct drm_encoder *encoder,
> + enum drm_bridge_attach_flags flags)
> +{
> + struct lt9611c *lt9611c = bridge_to_lt9611c(bridge);
I think it would be nice to ban the deprecated connector creation by adding
here:
if (!(flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR))
return -EINVAL;
and maybe log an error too. Look at other drivers which do this.
> +
> + return drm_bridge_attach(encoder, lt9611c->bridge.next_bridge, bridge,
> flags);
> +}
> +
> +static enum drm_mode_status
> +lt9611c_hdmi_tmds_char_rate_valid(const struct drm_bridge *bridge,
^^^^
Out of curiosity, what does "char" means here?
> +static void lt9611c_video_setup(struct lt9611c *lt9611c,
> + const struct drm_display_mode *mode)
> +{
> + struct device *dev = lt9611c->dev;
> + int ret;
> + u32 h_total, hactive, hsync_len, hfront_porch, hback_porch;
> + u32 v_total, vactive, vsync_len, vfront_porch, vback_porch;
> + u8 timing_data[22];
> + struct lt9611c_rsp rsp = {};
> + u8 framerate;
> + u8 vic = 0x00;
> + struct lt9611c_cmd cmd = {
> + .hdr = { LT9611C_FUNC_WRITE, LT9611C_TYPE_MIPI, 0x33,
> LT9611C_CMD_SEP },
> + .data = timing_data,
> + .data_len = ARRAY_SIZE(timing_data),
Nit: sizeof(timing_data) would be more correct. It is equivalent here
because it's a u8 array, but as a general rule it's better to ensure you
catch the entire buffer size, not the amount of elements which in other
cases might be larger than 1 byte.
> + };
> +
> + guard(mutex)(<9611c->mcu_lock);
> + h_total = mode->htotal;
> + hactive = mode->hdisplay;
> + hsync_len = mode->hsync_end - mode->hsync_start;
> + hfront_porch = mode->hsync_start - mode->hdisplay;
> + hback_porch = mode->htotal - mode->hsync_end;
> +
> + v_total = mode->vtotal;
> + vactive = mode->vdisplay;
> + vsync_len = mode->vsync_end - mode->vsync_start;
> + vfront_porch = mode->vsync_start - mode->vdisplay;
> + vback_porch = mode->vtotal - mode->vsync_end;
> + framerate = drm_mode_vrefresh(mode);
> + vic = drm_match_cea_mode(mode);
> +
> + dev_dbg(dev, "hactive=%d, vactive=%d\n", hactive, vactive);
> + dev_dbg(dev, "framerate=%d\n", framerate);
> + dev_dbg(dev, "vic = 0x%02x\n", vic);
> +
> + put_unaligned_be16(h_total, &timing_data[0]);
> + put_unaligned_be16(hactive, &timing_data[2]);
> + put_unaligned_be16(hfront_porch, &timing_data[4]);
> + put_unaligned_be16(hsync_len, &timing_data[6]);
> + put_unaligned_be16(hback_porch, &timing_data[8]);
> + put_unaligned_be16(v_total, &timing_data[10]);
> + put_unaligned_be16(vactive, &timing_data[12]);
> + put_unaligned_be16(vfront_porch, &timing_data[14]);
> + put_unaligned_be16(vsync_len, &timing_data[16]);
> + put_unaligned_be16(vback_porch, &timing_data[18]);
> + timing_data[20] = framerate;
> + timing_data[21] = vic;
You are kind us (ab)using an array as a manually-maintained
struct. Wouldn't it be a lot cleaner and readable if you declare a struct?
E.g.:
struct {
__be16 htotal;
__be16 hactive;
...
u8 framerate;
u8 vic;
} timing_data;
...
timing_data.htotal = cpu_to_be16(htotal);
timing_data.hactive = cpu_to_be16(hactive);
...
timing_data.framerate = framerate;
timing_data.vic = vic;
With that you can stop including unaligned.h too.
> +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,
> <9611c_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;
> +
> + const struct lt9611c_chip_data *cdata = i2c_get_match_data(client);
> +
> + if (!cdata)
> + return dev_err_probe(dev, -EINVAL, "no match data for
> device\n");
Nit: no empty line between a function call and its error checking if().
> +
> + lt9611c->chip_type = cdata->chip_type;
> + lt9611c->max_tmds_rate = cdata->max_tmds_rate;
> +
> + ret = devm_mutex_init(dev, <9611c->mcu_lock);
> + if (ret)
> + return dev_err_probe(dev, ret, "failed to init mutex\n");
> +
> + lt9611c->regmap = devm_regmap_init_i2c(client, <9611c_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");
> +
> + lt9611c->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> + if (IS_ERR(lt9611c->reset_gpio)) {
> + ret = PTR_ERR(lt9611c->reset_gpio);
> + 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;
Why not moving this inside lt9611c_regulator_init()?
Also, I _think_ lt9611c_regulator_init() could just
devm_regulator_bulk_get_enable() to do both things at once, but I'm not
sure that would be compatible with PM. If it's safe it would simplify the
code quite a lot, and also allow using devm_drm_bridge_add() below, making
the remove function almost empty.
> +
> + 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;
> +
Nit: no empty line.
> + } else if (lt9611c->fw_version == 0) {
> + if (!fw_updated) {
> + fw_updated = true;
> + lt9611c_unlock(lt9611c);
> + ret = lt9611c_firmware_upgrade(lt9611c);
> + if (ret < 0)
> + goto err_disable_regulators;
> + lt9611c_lock(lt9611c);
> + 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(<9611c->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;
> +
> + drm_bridge_add(<9611c->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);
> +
> + return 0;
> +
> +err_remove_bridge:
> + drm_bridge_remove(<9611c->bridge);
> + cancel_work_sync(<9611c->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);
> +
> + disable_irq(client->irq);
> + cancel_work_sync(<9611c->work);
> + drm_bridge_remove(<9611c->bridge);
> + regulator_bulk_disable(ARRAY_SIZE(lt9611c->supplies),
> lt9611c->supplies);
> + of_node_put(lt9611c->dsi1_node);
> + of_node_put(lt9611c->dsi0_node);
> +}
> +static struct i2c_device_id lt9611c_id[] = {
> + { "lontium,lt9611c", (kernel_ulong_t)<9611c_chip_data[CHIP_LT9611C]
> },
> + { "lontium,lt9611ex",
> (kernel_ulong_t)<9611c_chip_data[CHIP_LT9611EX] },
> + { "lontium,lt9611uxd",
> (kernel_ulong_t)<9611c_chip_data[CHIP_LT9611UXD] },
AFAIK there should be no vendor prefix for the i2c_device_id. Have a look
at the docs and other drivers for the best practice.
Luca
--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
