* [PATCH 1/2] chrome: lightbar: Report number of segments
@ 2026-01-24 8:58 Gwendal Grignou
2026-01-26 7:13 ` Tzung-Bi Shih
0 siblings, 1 reply; 3+ messages in thread
From: Gwendal Grignou @ 2026-01-24 8:58 UTC (permalink / raw)
To: tzungbi; +Cc: chrome-platform, Gwendal Grignou
Add attribue `num_segments` to return the number of exposed LED segments
in the lightbar. It can be smaller than the number of physical leds in
the lightbar.
Test: Check the attribute is present and returns a value when read.
Signed-off-by: Gwendal Grignou <gwendal@google.com>
---
drivers/platform/chrome/cros_ec_lightbar.c | 46 +++++++++++++++++++
.../linux/platform_data/cros_ec_commands.h | 11 +++++
2 files changed, 57 insertions(+)
diff --git a/drivers/platform/chrome/cros_ec_lightbar.c b/drivers/platform/chrome/cros_ec_lightbar.c
index 87634f6921b7..85f30c8dfba3 100644
--- a/drivers/platform/chrome/cros_ec_lightbar.c
+++ b/drivers/platform/chrome/cros_ec_lightbar.c
@@ -173,6 +173,50 @@ static ssize_t version_show(struct device *dev,
return sysfs_emit(buf, "%d %d\n", version, flags);
}
+static ssize_t num_segments_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ uint32_t num = 0;
+ struct cros_ec_dev *ec = to_cros_ec_dev(dev);
+ int ret;
+
+ ret = lb_throttle();
+ if (ret)
+ return ret;
+
+ struct ec_params_lightbar *param;
+ struct ec_response_lightbar *resp;
+ struct cros_ec_command *msg;
+
+ msg = alloc_lightbar_cmd_msg(ec);
+ if (!msg)
+ return -ENOMEM;
+
+ param = (struct ec_params_lightbar *)msg->data;
+ param->cmd = LIGHTBAR_CMD_GET_PARAMS_V3;
+ msg->outsize = sizeof(param->cmd);
+ msg->result = sizeof(resp->get_params_v3);
+ ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
+ if (ret < 0 && ret != -EINVAL)
+ goto exit;
+
+ if (msg->result == EC_RES_SUCCESS) {
+ resp = (struct ec_response_lightbar *)msg->data;
+ num = resp->get_params_v3.reported_led_num;
+ }
+
+ /*
+ * Anything else (ie, EC_RES_INVALID_COMMAND) - no direct control over
+ * LEDs, return that no leds are supported.
+ */
+ ret = 0;
+exit:
+ kfree(msg);
+ if (ret)
+ return ret;
+ return sysfs_emit(buf, "%d\n", num);
+}
+
static ssize_t brightness_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
@@ -505,6 +549,7 @@ static ssize_t userspace_control_store(struct device *dev,
/* Module initialization */
static DEVICE_ATTR_RW(interval_msec);
+static DEVICE_ATTR_RO(num_segments);
static DEVICE_ATTR_RO(version);
static DEVICE_ATTR_WO(brightness);
static DEVICE_ATTR_WO(led_rgb);
@@ -514,6 +559,7 @@ static DEVICE_ATTR_RW(userspace_control);
static struct attribute *__lb_cmds_attrs[] = {
&dev_attr_interval_msec.attr,
+ &dev_attr_num_segments.attr,
&dev_attr_version.attr,
&dev_attr_brightness.attr,
&dev_attr_led_rgb.attr,
diff --git a/include/linux/platform_data/cros_ec_commands.h b/include/linux/platform_data/cros_ec_commands.h
index 69294f79cc88..9cbf024f56c3 100644
--- a/include/linux/platform_data/cros_ec_commands.h
+++ b/include/linux/platform_data/cros_ec_commands.h
@@ -2005,6 +2005,14 @@ struct lightbar_params_v2_colors {
struct rgb_s color[8]; /* 0-3 are Google colors */
} __ec_todo_packed;
+struct lightbar_params_v3 {
+ /*
+ * Number of LEDs reported by the EC.
+ * May be less than the actual number of LEDs in the lightbar.
+ */
+ uint8_t reported_led_num;
+} __ec_todo_packed;
+
/* Lightbar program. */
#define EC_LB_PROG_LEN 192
struct lightbar_program {
@@ -2086,6 +2094,8 @@ struct ec_response_lightbar {
struct lightbar_params_v2_thresholds get_params_v2_thlds;
struct lightbar_params_v2_colors get_params_v2_colors;
+ struct lightbar_params_v3 get_params_v3;
+
struct __ec_todo_unpacked {
uint32_t num;
uint32_t flags;
@@ -2143,6 +2153,7 @@ enum lightbar_command {
LIGHTBAR_CMD_SET_PARAMS_V2_THRESHOLDS = 31,
LIGHTBAR_CMD_GET_PARAMS_V2_COLORS = 32,
LIGHTBAR_CMD_SET_PARAMS_V2_COLORS = 33,
+ LIGHTBAR_CMD_GET_PARAMS_V3 = 34,
LIGHTBAR_NUM_CMDS
};
--
2.52.0.457.g6b5491de43-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH 1/2] chrome: lightbar: Report number of segments
2026-01-24 8:58 [PATCH 1/2] chrome: lightbar: Report number of segments Gwendal Grignou
@ 2026-01-26 7:13 ` Tzung-Bi Shih
2026-01-26 8:54 ` Gwendal Grignou
0 siblings, 1 reply; 3+ messages in thread
From: Tzung-Bi Shih @ 2026-01-26 7:13 UTC (permalink / raw)
To: Gwendal Grignou; +Cc: chrome-platform, Gwendal Grignou
On Sat, Jan 24, 2026 at 12:58:55AM -0800, Gwendal Grignou wrote:
> Add attribue `num_segments` to return the number of exposed LED segments
> in the lightbar. It can be smaller than the number of physical leds in
> the lightbar.
>
> Test: Check the attribute is present and returns a value when read.
Please use "platform/chrome" prefix for the commit title.
> +static ssize_t num_segments_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + uint32_t num = 0;
`./scripts/checkpatch.pl --strict`:
CHECK: Prefer kernel type 'u32' over 'uint32_t'
> + struct cros_ec_dev *ec = to_cros_ec_dev(dev);
> + int ret;
> +
> + ret = lb_throttle();
> + if (ret)
> + return ret;
> +
> + struct ec_params_lightbar *param;
> + struct ec_response_lightbar *resp;
> + struct cros_ec_command *msg;
For clarity, I prefer to move the 3 declarations before calling lb_throttle()
in the case.
> +
> + msg = alloc_lightbar_cmd_msg(ec);
> + if (!msg)
> + return -ENOMEM;
> +
> + param = (struct ec_params_lightbar *)msg->data;
> + param->cmd = LIGHTBAR_CMD_GET_PARAMS_V3;
> + msg->outsize = sizeof(param->cmd);
> + msg->result = sizeof(resp->get_params_v3);
^^^^^^ insize
> + ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
> + if (ret < 0 && ret != -EINVAL)
> + goto exit;
> +
> + if (msg->result == EC_RES_SUCCESS) {
> + resp = (struct ec_response_lightbar *)msg->data;
> + num = resp->get_params_v3.reported_led_num;
> + }
> +
> + /*
> + * Anything else (ie, EC_RES_INVALID_COMMAND) - no direct control over
> + * LEDs, return that no leds are supported.
> + */
> + ret = 0;
> +exit:
> + kfree(msg);
> + if (ret)
> + return ret;
> + return sysfs_emit(buf, "%d\n", num);
^ `num` is an u32.
> +}
How about:
ret = sysfs_emit(buf, "%u\n", num);
exit:
kfree(msg);
return ret;
> diff --git a/include/linux/platform_data/cros_ec_commands.h b/include/linux/platform_data/cros_ec_commands.h
> index 69294f79cc88..9cbf024f56c3 100644
> --- a/include/linux/platform_data/cros_ec_commands.h
> +++ b/include/linux/platform_data/cros_ec_commands.h
> @@ -2005,6 +2005,14 @@ struct lightbar_params_v2_colors {
> struct rgb_s color[8]; /* 0-3 are Google colors */
> } __ec_todo_packed;
>
> +struct lightbar_params_v3 {
> + /*
> + * Number of LEDs reported by the EC.
> + * May be less than the actual number of LEDs in the lightbar.
> + */
> + uint8_t reported_led_num;
> +} __ec_todo_packed;
> +
> /* Lightbar program. */
> #define EC_LB_PROG_LEN 192
> struct lightbar_program {
> @@ -2086,6 +2094,8 @@ struct ec_response_lightbar {
> struct lightbar_params_v2_thresholds get_params_v2_thlds;
> struct lightbar_params_v2_colors get_params_v2_colors;
>
> + struct lightbar_params_v3 get_params_v3;
> +
> struct __ec_todo_unpacked {
> uint32_t num;
> uint32_t flags;
> @@ -2143,6 +2153,7 @@ enum lightbar_command {
> LIGHTBAR_CMD_SET_PARAMS_V2_THRESHOLDS = 31,
> LIGHTBAR_CMD_GET_PARAMS_V2_COLORS = 32,
> LIGHTBAR_CMD_SET_PARAMS_V2_COLORS = 33,
> + LIGHTBAR_CMD_GET_PARAMS_V3 = 34,
> LIGHTBAR_NUM_CMDS
> };
Haven't seen the change in
https://chromium.googlesource.com/chromiumos/platform/ec/+/refs/heads/main/include/ec_commands.h,
do we need to wait until the change landed in EC firmware?
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH 1/2] chrome: lightbar: Report number of segments
2026-01-26 7:13 ` Tzung-Bi Shih
@ 2026-01-26 8:54 ` Gwendal Grignou
0 siblings, 0 replies; 3+ messages in thread
From: Gwendal Grignou @ 2026-01-26 8:54 UTC (permalink / raw)
To: Tzung-Bi Shih; +Cc: Gwendal Grignou, chrome-platform
On Sun, Jan 25, 2026 at 11:13 PM Tzung-Bi Shih <tzungbi@kernel.org> wrote:
>
> On Sat, Jan 24, 2026 at 12:58:55AM -0800, Gwendal Grignou wrote:
> > Add attribue `num_segments` to return the number of exposed LED segments
> > in the lightbar. It can be smaller than the number of physical leds in
> > the lightbar.
> >
> > Test: Check the attribute is present and returns a value when read.
>
> Please use "platform/chrome" prefix for the commit title.
Done (in v2).
>
> > +static ssize_t num_segments_show(struct device *dev,
> > + struct device_attribute *attr, char *buf)
> > +{
> > + uint32_t num = 0;
>
> `./scripts/checkpatch.pl --strict`:
> CHECK: Prefer kernel type 'u32' over 'uint32_t'
I kept `uint...` to be consistent with the rest of the code.
>
> > + struct cros_ec_dev *ec = to_cros_ec_dev(dev);
> > + int ret;
> > +
> > + ret = lb_throttle();
> > + if (ret)
> > + return ret;
> > +
> > + struct ec_params_lightbar *param;
> > + struct ec_response_lightbar *resp;
> > + struct cros_ec_command *msg;
>
> For clarity, I prefer to move the 3 declarations before calling lb_throttle()
> in the case.
Done
>
> > +
> > + msg = alloc_lightbar_cmd_msg(ec);
> > + if (!msg)
> > + return -ENOMEM;
> > +
> > + param = (struct ec_params_lightbar *)msg->data;
> > + param->cmd = LIGHTBAR_CMD_GET_PARAMS_V3;
> > + msg->outsize = sizeof(param->cmd);
> > + msg->result = sizeof(resp->get_params_v3);
> ^^^^^^ insize
>
> > + ret = cros_ec_cmd_xfer_status(ec->ec_dev, msg);
> > + if (ret < 0 && ret != -EINVAL)
> > + goto exit;
> > +
> > + if (msg->result == EC_RES_SUCCESS) {
> > + resp = (struct ec_response_lightbar *)msg->data;
> > + num = resp->get_params_v3.reported_led_num;
> > + }
> > +
> > + /*
> > + * Anything else (ie, EC_RES_INVALID_COMMAND) - no direct control over
> > + * LEDs, return that no leds are supported.
> > + */
> > + ret = 0;
> > +exit:
> > + kfree(msg);
> > + if (ret)
> > + return ret;
> > + return sysfs_emit(buf, "%d\n", num);
> ^ `num` is an u32.
> > +}
>
> How about:
>
> ret = sysfs_emit(buf, "%u\n", num);
> exit:
> kfree(msg);
> return ret;
Done.
>
>
> > diff --git a/include/linux/platform_data/cros_ec_commands.h b/include/linux/platform_data/cros_ec_commands.h
> > index 69294f79cc88..9cbf024f56c3 100644
> > --- a/include/linux/platform_data/cros_ec_commands.h
> > +++ b/include/linux/platform_data/cros_ec_commands.h
> > @@ -2005,6 +2005,14 @@ struct lightbar_params_v2_colors {
> > struct rgb_s color[8]; /* 0-3 are Google colors */
> > } __ec_todo_packed;
> >
> > +struct lightbar_params_v3 {
> > + /*
> > + * Number of LEDs reported by the EC.
> > + * May be less than the actual number of LEDs in the lightbar.
> > + */
> > + uint8_t reported_led_num;
> > +} __ec_todo_packed;
> > +
> > /* Lightbar program. */
> > #define EC_LB_PROG_LEN 192
> > struct lightbar_program {
> > @@ -2086,6 +2094,8 @@ struct ec_response_lightbar {
> > struct lightbar_params_v2_thresholds get_params_v2_thlds;
> > struct lightbar_params_v2_colors get_params_v2_colors;
> >
> > + struct lightbar_params_v3 get_params_v3;
> > +
> > struct __ec_todo_unpacked {
> > uint32_t num;
> > uint32_t flags;
> > @@ -2143,6 +2153,7 @@ enum lightbar_command {
> > LIGHTBAR_CMD_SET_PARAMS_V2_THRESHOLDS = 31,
> > LIGHTBAR_CMD_GET_PARAMS_V2_COLORS = 32,
> > LIGHTBAR_CMD_SET_PARAMS_V2_COLORS = 33,
> > + LIGHTBAR_CMD_GET_PARAMS_V3 = 34,
> > LIGHTBAR_NUM_CMDS
> > };
>
> Haven't seen the change in
> https://chromium.googlesource.com/chromiumos/platform/ec/+/refs/heads/main/include/ec_commands.h,
> do we need to wait until the change landed in EC firmware?
For reference, crrev.com/c/7515877. Will post v2 once the change lands.
^ permalink raw reply [flat|nested] 3+ messages in thread
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