* [PATCH v2 1/2] HID: lg-g15: add LCD contrast LED
2026-11-09 17:17 [PATCH v2 0/2] HID: lg-g15: G15 v2 contrast and game-mode LEDs Torstein Eide
@ 2026-11-09 17:17 ` Torstein Eide
2026-11-09 17:17 ` [PATCH v2 2/2] HID: lg-g15: report Super-key-lock state on G15 v2's keyboard interface Torstein Eide
1 sibling, 0 replies; 3+ messages in thread
From: Torstein Eide @ 2026-11-09 17:17 UTC (permalink / raw)
To: Jiri Kosina, Benjamin Tissoires
Cc: Hans de Goede, Maoyi Xie, linux-input, linux-kernel
Wire values ({2, 32, 129, value}) match libg15's setLCDContrast()
byte-for-byte.
Tested on Logitech G15v2.
Based on libg15.c.
Signed-off-by: Torstein Eide <torsteine+linux@gmail.com>
Based-on-work-by: Philip Lawatsch <philip@lawatsch.at>
Based-on-work-by: Alex Ibrado <alex@ibrado.org>
Based-on-work-by: Anthony J. Mirabella <mirabeaj@gmail.com>
Based-on-work-by: Mike Lampard <mlampard@users.sourceforge.net>
Assisted-by: Claude:claude-sonnet-5
---
drivers/hid/hid-lg-g15.c | 119 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 117 insertions(+), 2 deletions(-)
diff --git a/drivers/hid/hid-lg-g15.c b/drivers/hid/hid-lg-g15.c
index 02ef3e2094b4..3827c66ca3a9 100644
--- a/drivers/hid/hid-lg-g15.c
+++ b/drivers/hid/hid-lg-g15.c
@@ -59,7 +59,16 @@ enum lg_g15_led_type {
LG_G15_MACRO_PRESET2,
LG_G15_MACRO_PRESET3,
LG_G15_MACRO_RECORD,
- LG_G15_LED_MAX
+ LG_G15_LED_MAX,
+ /*
+ * LCD contrast uses a different feature-report sub-format than the
+ * brightness/macro fields above (see lg_g15_contrast_set()) and has
+ * no hardware readback, so it lives outside [0, LG_G15_LED_MAX) to
+ * avoid being swept into the G13/macro loops bounded by
+ * LG_G15_LED_MAX. G15/G15 v2 only; registered explicitly.
+ */
+ LG_G15_LCD_CONTRAST = LG_G15_LED_MAX,
+ LG_G15_LED_ARRAY_SIZE
};
struct g13_input_report {
@@ -89,9 +98,10 @@ struct lg_g15_data {
struct input_dev *input_js; /* Separate joystick device for G13. */
struct hid_device *hdev;
enum lg_g15_model model;
- struct lg_g15_led leds[LG_G15_LED_MAX];
+ struct lg_g15_led leds[LG_G15_LED_ARRAY_SIZE];
bool game_mode_enabled;
bool backlight_disabled; /* true == HW backlight toggled *OFF* */
+ bool lcd_contrast_set; /* LCD contrast written at least once */
};
/********* G13 LED functions ***********/
@@ -365,6 +375,69 @@ static int lg_g15_led_set(struct led_classdev *led_cdev,
return ret;
}
+/*
+ * LCD contrast, report 2 field 32: {2, 32, 129, value}, value in
+ * {18, 22, 26} for low/medium/high. Distinct sub-format from the
+ * brightness/macro fields (value sits in byte 3, not byte 2, and byte 2 is
+ * a fixed marker rather than the field selector) and has no GET_REPORT
+ * readback, so brightness_get just returns the last value we set.
+ */
+/* Must be called with g15->mutex held */
+static int lg_g15_contrast_write(struct lg_g15_data *g15,
+ enum led_brightness brightness)
+{
+ static const u8 contrast_values[] = { 18, 22, 26 };
+ int ret;
+
+ /*
+ * The LED core does not clamp to max_brightness on every path (a
+ * delayed set passes the raw sysfs value), so clamp here.
+ */
+ brightness = min_t(enum led_brightness, brightness,
+ ARRAY_SIZE(contrast_values) - 1);
+
+ g15->transfer_buf[0] = LG_G15_FEATURE_REPORT;
+ g15->transfer_buf[1] = 32;
+ g15->transfer_buf[2] = 129;
+ g15->transfer_buf[3] = contrast_values[brightness];
+
+ ret = hid_hw_raw_request(g15->hdev, LG_G15_FEATURE_REPORT,
+ g15->transfer_buf, 4,
+ HID_FEATURE_REPORT, HID_REQ_SET_REPORT);
+ if (ret != 4) {
+ hid_err(g15->hdev, "Error setting LCD contrast: %d\n", ret);
+ return (ret < 0) ? ret : -EIO;
+ }
+
+ g15->leds[LG_G15_LCD_CONTRAST].brightness = brightness;
+ g15->lcd_contrast_set = true;
+ return 0;
+}
+
+static int lg_g15_contrast_set(struct led_classdev *led_cdev,
+ enum led_brightness brightness)
+{
+ struct lg_g15_data *g15 = dev_get_drvdata(led_cdev->dev->parent);
+ int ret;
+
+ if (led_cdev->flags & LED_UNREGISTERING)
+ return 0;
+
+ mutex_lock(&g15->mutex);
+ ret = lg_g15_contrast_write(g15, brightness);
+ mutex_unlock(&g15->mutex);
+
+ return ret;
+}
+
+static enum led_brightness lg_g15_contrast_get(struct led_classdev *led_cdev)
+{
+ struct lg_g15_led *g15_led =
+ container_of(led_cdev, struct lg_g15_led, cdev);
+
+ return g15_led->brightness;
+}
+
static void lg_g15_leds_changed_work(struct work_struct *work)
{
struct lg_g15_data *g15 = container_of(work, struct lg_g15_data, work);
@@ -1017,6 +1090,13 @@ static int lg_g15_register_led(struct lg_g15_data *g15, int i, const char *name)
break;
case LG_G15:
case LG_G15_V2:
+ if (i == LG_G15_LCD_CONTRAST) {
+ g15->leds[i].cdev.brightness_set_blocking = lg_g15_contrast_set;
+ g15->leds[i].cdev.brightness_get = lg_g15_contrast_get;
+ g15->leds[i].cdev.max_brightness = 2;
+ ret = devm_led_classdev_register(&g15->hdev->dev, &g15->leds[i].cdev);
+ break;
+ }
g15->leds[i].cdev.brightness_get = lg_g15_led_get;
fallthrough;
case LG_Z10:
@@ -1333,6 +1413,14 @@ static int lg_g15_probe(struct hid_device *hdev, const struct hid_device_id *id)
goto error_hw_stop;
}
+ /* The G11 shares the LG_G15 model but has no LCD */
+ if ((g15->model == LG_G15 && hdev->product != USB_DEVICE_ID_LOGITECH_G11) ||
+ g15->model == LG_G15_V2) {
+ ret = lg_g15_register_led(g15, LG_G15_LCD_CONTRAST, "g15::lcd_contrast");
+ if (ret)
+ goto error_hw_stop;
+ }
+
return 0;
error_hw_stop:
@@ -1389,12 +1477,39 @@ static void lg_g15_remove(struct hid_device *hdev)
hid_hw_stop(hdev);
}
+/*
+ * The LCD does not retain its contrast across a USB reset or power loss;
+ * re-apply the last value userspace set, if any.
+ */
+static int lg_g15_resume(struct hid_device *hdev)
+{
+ struct lg_g15_data *g15 = hid_get_drvdata(hdev);
+ struct lg_g15_led *contrast;
+
+ if (!g15)
+ return 0;
+
+ contrast = &g15->leds[LG_G15_LCD_CONTRAST];
+ if (!contrast->cdev.dev)
+ return 0;
+
+ /* Under the mutex, so a concurrent contrast set cannot be undone */
+ mutex_lock(&g15->mutex);
+ if (g15->lcd_contrast_set)
+ lg_g15_contrast_write(g15, contrast->brightness);
+ mutex_unlock(&g15->mutex);
+
+ return 0;
+}
+
static struct hid_driver lg_g15_driver = {
.name = "lg-g15",
.id_table = lg_g15_devices,
.raw_event = lg_g15_raw_event,
.probe = lg_g15_probe,
.remove = lg_g15_remove,
+ .resume = lg_g15_resume,
+ .reset_resume = lg_g15_resume,
};
module_hid_driver(lg_g15_driver);
--
2.53.0
^ permalink raw reply [flat|nested] 3+ messages in thread* [PATCH v2 2/2] HID: lg-g15: report Super-key-lock state on G15 v2's keyboard interface
2026-11-09 17:17 [PATCH v2 0/2] HID: lg-g15: G15 v2 contrast and game-mode LEDs Torstein Eide
2026-11-09 17:17 ` [PATCH v2 1/2] HID: lg-g15: add LCD contrast LED Torstein Eide
@ 2026-11-09 17:17 ` Torstein Eide
1 sibling, 0 replies; 3+ messages in thread
From: Torstein Eide @ 2026-11-09 17:17 UTC (permalink / raw)
To: Jiri Kosina, Benjamin Tissoires
Cc: Hans de Goede, Maoyi Xie, linux-input, linux-kernel
The G15 v2 exposes a second USB HID interface (046D:C226) previously
left to hid-generic, which reports the Super-key-lock ("Game Mode")
state on report 3. Bind it as LG_G15_V2_KBD: keep default hid-input
behavior for normal typing, and additionally decode report 3 to expose
the lock state as a read-only g15::game_mode LED.
Tested on Logitech G15v2.
Signed-off-by: Torstein Eide <torsteine+linux@gmail.com>
Assisted-by: Claude:claude-sonnet-5
---
drivers/hid/hid-ids.h | 1 +
drivers/hid/hid-lg-g15.c | 230 ++++++++++++++++++++++++++++++++++++++-
2 files changed, 227 insertions(+), 4 deletions(-)
diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
index 91319aa6516d..44ebf2a0accc 100644
--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@ -950,6 +950,7 @@
#define USB_DEVICE_ID_LOGITECH_G13 0xc21c
#define USB_DEVICE_ID_LOGITECH_G15_LCD 0xc222
#define USB_DEVICE_ID_LOGITECH_G11 0xc225
+#define USB_DEVICE_ID_LOGITECH_G15_V2_KBD 0xc226
#define USB_DEVICE_ID_LOGITECH_G15_V2_LCD 0xc227
#define USB_DEVICE_ID_LOGITECH_G510 0xc22d
#define USB_DEVICE_ID_LOGITECH_G510_USB_AUDIO 0xc22e
diff --git a/drivers/hid/hid-lg-g15.c b/drivers/hid/hid-lg-g15.c
index 3827c66ca3a9..998023ad272d 100644
--- a/drivers/hid/hid-lg-g15.c
+++ b/drivers/hid/hid-lg-g15.c
@@ -12,6 +12,7 @@
#include <linux/module.h>
#include <linux/random.h>
#include <linux/sched.h>
+#include <linux/spinlock.h>
#include <linux/usb.h>
#include <linux/wait.h>
#include <dt-bindings/leds/common.h>
@@ -45,7 +46,8 @@
enum lg_g15_model {
LG_G13,
LG_G15,
- LG_G15_V2,
+ LG_G15_V2, /* 046D:C227, GamePanel LCD iface */
+ LG_G15_V2_KBD, /* 046D:C226, keyboard/consumer-ctrl iface, not the LCD */
LG_G510,
LG_G510_USB_AUDIO,
LG_Z10,
@@ -104,6 +106,19 @@ struct lg_g15_data {
bool lcd_contrast_set; /* LCD contrast written at least once */
};
+/*
+ * State for the G15 v2's separate keyboard + consumer-control USB device
+ * (046D:C226). Unlike lg_g15_data above, this is not the GamePanel LCD
+ * interface: it carries normal typing (left to generic hid-input) plus one
+ * extra report we care about, so it only needs a small amount of state.
+ */
+struct lg_g15_kbd_data {
+ struct led_classdev led; /* g15::game_mode, read-only */
+ spinlock_t lock; /* Protects super_lock and events */
+ bool super_lock; /* Cached HW state of the Super/Windows-key lock */
+ unsigned int events; /* Report 3 input reports seen so far */
+};
+
/********* G13 LED functions ***********/
/*
* G13 retains no state across power cycles, and always powers up with the backlight on,
@@ -699,6 +714,8 @@ static int lg_g15_get_initial_led_brightness(struct lg_g15_data *g15)
* the LCD and touch keys part of the speakers.
*/
return 0;
+ case LG_G15_V2_KBD:
+ break; /* Never reached, this model has no lg_g15_data */
}
return -EINVAL; /* Never reached */
}
@@ -963,11 +980,173 @@ static int lg_g510_leds_event(struct lg_g15_data *g15, u8 *data)
return 0;
}
+/********* G15 v2 keyboard interface functions *********/
+
+/* Report 3, byte 1 bit 0: Super/Windows key lock state ("Game Mode") */
+#define LG_G15_V2_KBD_GAME_MODE_REPORT 0x03
+
+/*
+ * The G15 v2's keyboard device uses struct lg_g15_kbd_data as drvdata, not
+ * struct lg_g15_data. This is the one check used by every entry point to
+ * tell the two apart.
+ */
+static bool lg_g15_is_v2_kbd(struct hid_device *hdev)
+{
+ return hdev->vendor == USB_VENDOR_ID_LOGITECH &&
+ hdev->product == USB_DEVICE_ID_LOGITECH_G15_V2_KBD;
+}
+
+static enum led_brightness lg_g15_v2_kbd_super_lock_get(struct led_classdev *led_cdev)
+{
+ struct lg_g15_kbd_data *kbd = container_of(led_cdev, struct lg_g15_kbd_data, led);
+
+ return kbd->super_lock;
+}
+
+/* Must be called with kbd->lock held */
+static void lg_g15_v2_kbd_set_super_lock(struct lg_g15_kbd_data *kbd, bool super_lock)
+{
+ if (super_lock == kbd->super_lock)
+ return;
+
+ kbd->super_lock = super_lock;
+ led_classdev_notify_brightness_hw_changed(&kbd->led, super_lock);
+}
+
+/* Fetches the current lock state, which may already be on at probe/resume. */
+static int lg_g15_v2_kbd_get_super_lock(struct hid_device *hdev, bool *super_lock)
+{
+ u8 *buf;
+ int ret;
+
+ buf = kzalloc(2, GFP_KERNEL); /* DMA-able, not on the stack */
+ if (!buf)
+ return -ENOMEM;
+
+ ret = hid_hw_raw_request(hdev, LG_G15_V2_KBD_GAME_MODE_REPORT, buf, 2,
+ HID_INPUT_REPORT, HID_REQ_GET_REPORT);
+ if (ret == 2 && buf[0] == LG_G15_V2_KBD_GAME_MODE_REPORT) {
+ *super_lock = buf[1] & 0x01;
+ ret = 0;
+ } else {
+ hid_dbg(hdev, "Error reading Super-key-lock state: %d\n", ret);
+ ret = (ret < 0) ? ret : -EIO;
+ }
+
+ kfree(buf);
+ return ret;
+}
+
+/*
+ * Re-reads the lock state on resume. Input reports keep arriving while the
+ * GET_REPORT is in flight; if one did, it is newer than what we read, so
+ * keep the state it set.
+ */
+static void lg_g15_v2_kbd_refresh_super_lock(struct hid_device *hdev,
+ struct lg_g15_kbd_data *kbd)
+{
+ unsigned long flags;
+ unsigned int events;
+ bool super_lock;
+
+ spin_lock_irqsave(&kbd->lock, flags);
+ events = kbd->events;
+ spin_unlock_irqrestore(&kbd->lock, flags);
+
+ if (lg_g15_v2_kbd_get_super_lock(hdev, &super_lock))
+ return;
+
+ spin_lock_irqsave(&kbd->lock, flags);
+ if (kbd->events == events)
+ lg_g15_v2_kbd_set_super_lock(kbd, super_lock);
+ spin_unlock_irqrestore(&kbd->lock, flags);
+}
+
+/* Decodes report 3 and mirrors the Super-key-lock bit into the game_mode LED. */
+static int lg_g15_v2_kbd_raw_event(struct hid_device *hdev, u8 *data, int size)
+{
+ struct lg_g15_kbd_data *kbd = hid_get_drvdata(hdev);
+ unsigned long flags;
+
+ if (!kbd || data[0] != LG_G15_V2_KBD_GAME_MODE_REPORT || size != 2)
+ return 0; /* Not our report, or the non-consumer-control interface */
+
+ spin_lock_irqsave(&kbd->lock, flags);
+ kbd->events++;
+ lg_g15_v2_kbd_set_super_lock(kbd, data[1] & 0x01);
+ spin_unlock_irqrestore(&kbd->lock, flags);
+
+ return 0;
+}
+
+/*
+ * The G15 v2's keyboard USB device exposes two HID interfaces of its own
+ * (boot keyboard + consumer control); both match this same USB product ID,
+ * so this probe runs once per interface. Only the consumer-control one
+ * carries report 3, so the LED is only registered there; the other gets
+ * plain generic hid-input and nothing else, same as if hid-generic had
+ * bound it.
+ */
+static int lg_g15_v2_kbd_probe(struct hid_device *hdev)
+{
+ struct hid_report_enum *rep_enum;
+ struct hid_report *rep;
+ bool has_game_mode_report = false;
+ struct lg_g15_kbd_data *kbd;
+ int ret;
+
+ hdev->quirks |= HID_QUIRK_INPUT_PER_APP; /* As hid-generic does */
+
+ ret = hid_parse(hdev);
+ if (ret)
+ return ret;
+
+ rep_enum = &hdev->report_enum[HID_INPUT_REPORT];
+ list_for_each_entry(rep, &rep_enum->report_list, list) {
+ if (rep->id == LG_G15_V2_KBD_GAME_MODE_REPORT)
+ has_game_mode_report = true; /* This is the consumer-control interface */
+ }
+
+ ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT); /* Plain generic keyboard input */
+ if (ret)
+ return ret;
+
+ if (!has_game_mode_report)
+ return 0; /* Boot-keyboard interface, nothing more to do */
+
+ kbd = devm_kzalloc(&hdev->dev, sizeof(*kbd), GFP_KERNEL);
+ if (!kbd)
+ return 0; /* Non-fatal, keyboard input still works without the LED */
+
+ spin_lock_init(&kbd->lock);
+
+ /* Register the LED with the current state, not a default of off */
+ lg_g15_v2_kbd_get_super_lock(hdev, &kbd->super_lock);
+
+ kbd->led.name = "g15::game_mode";
+ kbd->led.max_brightness = 1;
+ kbd->led.brightness_get = lg_g15_v2_kbd_super_lock_get;
+ kbd->led.flags = LED_BRIGHT_HW_CHANGED; /* Enables the hw_changed notify below */
+
+ ret = devm_led_classdev_register(&hdev->dev, &kbd->led);
+ if (ret)
+ return 0; /* Non-fatal, keyboard input still works without the LED */
+
+ /* hid-core does not deliver input reports until probe() returns */
+ hid_set_drvdata(hdev, kbd);
+
+ return 0;
+}
+
static int lg_g15_raw_event(struct hid_device *hdev, struct hid_report *report,
u8 *data, int size)
{
- struct lg_g15_data *g15 = hid_get_drvdata(hdev);
+ struct lg_g15_data *g15;
+
+ if (lg_g15_is_v2_kbd(hdev)) /* Separate kbd/consumer-ctrl dev */
+ return lg_g15_v2_kbd_raw_event(hdev, data, size);
+ g15 = hid_get_drvdata(hdev);
if (!g15)
return 0;
@@ -997,6 +1176,8 @@ static int lg_g15_raw_event(struct hid_device *hdev, struct hid_report *report,
if (data[0] == LG_G510_INPUT_KBD_BACKLIGHT && size == 2)
return lg_g510_leds_event(g15, data);
break;
+ case LG_G15_V2_KBD:
+ break; /* Never reached, handled via lg_g15_is_v2_kbd() above */
}
return 0;
@@ -1135,6 +1316,9 @@ static int lg_g15_register_led(struct lg_g15_data *g15, int i, const char *name)
ret = devm_led_classdev_register(&g15->hdev->dev, &g15->leds[i].cdev);
}
break;
+ case LG_G15_V2_KBD:
+ ret = -EINVAL; /* Never reached, this model has no lg_g15_data LEDs */
+ break;
}
return ret;
@@ -1210,6 +1394,12 @@ static int lg_g15_probe(struct hid_device *hdev, const struct hid_device_id *id)
struct hid_report *rep;
int ret, i, gkeys = 0;
+ if (lg_g15_is_v2_kbd(hdev)) /* Not the GamePanel LCD interface */
+ return lg_g15_v2_kbd_probe(hdev);
+
+ if (id->driver_data == LG_G15_V2_KBD) /* e.g. a mismatching new_id */
+ return -ENODEV;
+
hdev->quirks |= HID_QUIRK_INPUT_PER_APP;
ret = hid_parse(hdev);
@@ -1292,6 +1482,8 @@ static int lg_g15_probe(struct hid_device *hdev, const struct hid_device_id *id)
case LG_Z10:
connect_mask = HID_CONNECT_HIDRAW;
break;
+ case LG_G15_V2_KBD:
+ break; /* Never reached, rejected above */
}
ret = hid_hw_start(hdev, connect_mask);
@@ -1446,6 +1638,16 @@ static const struct hid_device_id lg_g15_devices[] = {
{ HID_USB_DEVICE(USB_VENDOR_ID_LOGITECH,
USB_DEVICE_ID_LOGITECH_G15_V2_LCD),
.driver_data = LG_G15_V2 },
+ /*
+ * The G15 v2's keyboard + consumer-control USB device (a separate
+ * device from the GamePanel LCD one above, on the keyboard's builtin
+ * hub). Normal typing is handled by generic hid-input; we only bind
+ * this to also expose the Super/Windows-key-lock ("Game Mode") state,
+ * see lg_g15_v2_kbd_probe().
+ */
+ { HID_USB_DEVICE(USB_VENDOR_ID_LOGITECH,
+ USB_DEVICE_ID_LOGITECH_G15_V2_KBD),
+ .driver_data = LG_G15_V2_KBD },
/* G510 without a headset plugged in */
{ HID_USB_DEVICE(USB_VENDOR_ID_LOGITECH,
USB_DEVICE_ID_LOGITECH_G510),
@@ -1464,7 +1666,18 @@ MODULE_DEVICE_TABLE(hid, lg_g15_devices);
static void lg_g15_remove(struct hid_device *hdev)
{
- struct lg_g15_data *g15 = hid_get_drvdata(hdev);
+ struct lg_g15_data *g15;
+
+ /*
+ * The G15 v2's keyboard device uses struct lg_g15_kbd_data, not
+ * lg_g15_data below; it has nothing to clean up beyond hid_hw_stop().
+ */
+ if (lg_g15_is_v2_kbd(hdev)) {
+ hid_hw_stop(hdev);
+ return;
+ }
+
+ g15 = hid_get_drvdata(hdev);
/*
* g15->work is only initialized for the models that schedule it
@@ -1483,9 +1696,18 @@ static void lg_g15_remove(struct hid_device *hdev)
*/
static int lg_g15_resume(struct hid_device *hdev)
{
- struct lg_g15_data *g15 = hid_get_drvdata(hdev);
+ struct lg_g15_data *g15;
struct lg_g15_led *contrast;
+ if (lg_g15_is_v2_kbd(hdev)) {
+ struct lg_g15_kbd_data *kbd = hid_get_drvdata(hdev);
+
+ if (kbd)
+ lg_g15_v2_kbd_refresh_super_lock(hdev, kbd);
+ return 0;
+ }
+
+ g15 = hid_get_drvdata(hdev);
if (!g15)
return 0;
--
2.53.0
^ permalink raw reply [flat|nested] 3+ messages in thread