tech@,

A new quirk UVIDEO_FLAG_RENEGOTIATE_AFTER_SET_ALT from this thread [1] is
required for at least one more camera: LG UltraFine Display Camera. And this
camera allows to discover a bug with bulk processing inside uvideo: here
usbd_get_xfer_status is missing and current code is built on the assumption
that device always returns dwMaxPayloadTransferSize bytes.

Here is a diff that adds the missing usbd_get_xfer_status and the quirk.

Feedback? Tests? Ok?

Index: sys/dev/usb/uvideo.c
===================================================================
RCS file: /home/cvs/src/sys/dev/usb/uvideo.c,v
diff -u -p -r1.224 uvideo.c
--- sys/dev/usb/uvideo.c	30 Nov 2024 17:47:23 -0000	1.224
+++ sys/dev/usb/uvideo.c	30 Nov 2024 22:20:00 -0000
@@ -386,6 +386,12 @@ const struct uvideo_devs {
 	    NULL,
 	    UVIDEO_FLAG_RENEGOTIATE_AFTER_SET_ALT
 	},
+	{   /* Needs renegotiate after setting alternate interface */
+	    { USB_VENDOR_LG, USB_PRODUCT_LG_ULTRA_FINE_VIDEO },
+	    NULL,
+	    NULL,
+	    UVIDEO_FLAG_RENEGOTIATE_AFTER_SET_ALT
+	},
 };
 #define uvideo_lookup(v, p) \
 	((const struct uvideo_devs *)usb_lookup(uvideo_devs, v, p))
@@ -2051,6 +2057,9 @@ uvideo_vs_start_bulk_thread(void *arg)
 			    DEVNAME(sc), usbd_errstr(error));
 			break;
 		}
+
+		usbd_get_xfer_status(sc->sc_vs_cur->bxfer.xfer,
+		    NULL, NULL, &size, NULL);
 
 		DPRINTF(2, "%s: *** buffer len = %d\n", DEVNAME(sc), size);
 
Index: sys/dev/usb/usbdevs
===================================================================
RCS file: /home/cvs/src/sys/dev/usb/usbdevs,v
diff -u -p -r1.772 usbdevs
--- sys/dev/usb/usbdevs	30 Nov 2024 17:41:57 -0000	1.772
+++ sys/dev/usb/usbdevs	30 Nov 2024 22:21:37 -0000
@@ -2704,6 +2704,7 @@ product LEXMARK S2450		0x0009	Optra S 24
 /* LG products */
 product LG RTL8153		0x9819	RTL8153
 product LG RTL8153B		0x9820	RTL8153
+product LG ULTRA_FINE_VIDEO	0x9a68	LG UltraFine Display Camera
 
 /* Liebert products */
 product LIEBERT UPS		0xffff	UPS
Index: share/man/man4/uvideo.4
===================================================================
RCS file: /home/cvs/src/share/man/man4/uvideo.4,v
diff -u -p -r1.44 uvideo.4
--- share/man/man4/uvideo.4	30 Nov 2024 20:15:03 -0000	1.44
+++ share/man/man4/uvideo.4	30 Nov 2024 22:07:06 -0000
@@ -47,6 +47,8 @@ Jabra PanaCast 20
 .It
 Lenovo EasyCamera (Lenovo IdeaPad s10e Notebooks)
 .It
+LG UltraFine Display Camera
+.It
 Logitech QuickCam for Notebooks Pro
 .It
 Logitech QuickCam Communicate Deluxe


Footnotes:
[1]  https://marc.info/?t=173266150800001&r=1&w=2

-- 
wbr, Kirill