On 2025-09-09 02.59, Stuart wrote:
> What does logitech-dj do differently to the generic HID driver around the LEDs?
> The caps lock LED works perfectly fine with the generic driver.
>
> If that goes nowhere, surely I could do a packet capture from Linux, with and
> without the logitech-dj driver active?
>
> Stuart
Since the first diff you tested was supposed to send the exact same
report as the generic hid driver, I incorrectly came to the conclusion
that the Logitech kernel driver must be doing something different.
Turns out the report ID was being forced to 0 when it should have been 1.
Can you try applying the following?
diff --git a/drivers/hid/hid-logitech-dj.c b/drivers/hid/hid-logitech-dj.c
index 00a975b70f59..9b3b00d69079 100644
--- a/drivers/hid/hid-logitech-dj.c
+++ b/drivers/hid/hid-logitech-dj.c
@@ -78,6 +78,7 @@
#define REPORT_TYPE_SYSTEM_CONTROL 0x04
#define REPORT_TYPE_MEDIA_CENTER 0x08
#define REPORT_TYPE_LEDS 0x0E
+#define REPORT_TYPE_LEDS_LIGHTSPEED 0x01
/* RF Report types bitfield */
#define STD_KEYBOARD BIT(1)
@@ -1455,16 +1456,28 @@ static int logi_dj_ll_raw_request(struct hid_device *hid,
count, report_type, reqtype);
}
- if (buf[0] != REPORT_TYPE_LEDS)
- return -EINVAL;
+ /* This Lightspeed receiver type uses a different LED report ID */
+ if (djrcv_dev->type == recvr_type_gaming_hidpp_ls_1_3) {
+ if (buf[0] != REPORT_TYPE_LEDS_LIGHTSPEED)
+ return -EINVAL;
+ } else {
+ if (buf[0] != REPORT_TYPE_LEDS)
+ return -EINVAL;
+ }
if (djrcv_dev->type != recvr_type_dj && count >= 2) {
+ unsigned char reportnum_led = 0;
if (!djrcv_dev->keyboard) {
hid_warn(hid, "Received REPORT_TYPE_LEDS request before the keyboard interface was enumerated\n");
return 0;
}
+
+ /* This Lightspeed receiver expects LED reports with the ID defined in the HID descriptor */
+ if (djrcv_dev->type == recvr_type_gaming_hidpp_ls_1_3)
+ reportnum_led = reportnum;
+
/* usbhid overrides the report ID and ignores the first byte */
- return hid_hw_raw_request(djrcv_dev->keyboard, 0, buf, count,
+ return hid_hw_raw_request(djrcv_dev->keyboard, reportnum_led, buf, count,
report_type, reqtype);
}
