From f97e96c303d689708f7f713d8f3afcc31f1237e9 Mon Sep 17 00:00:00 2001 From: Oliver Neukum Date: Tue, 17 Mar 2026 09:41:10 +0100 Subject: [PATCH] cdc-acm: new quirk for EPSON HMD This device has a union descriptor that is just garbage and needs a custom descriptor. In principle this could be done with a (conditionally activated) heuristic. That would match more devices without a need for defining a new quirk. However, this always carries the risk that the heuristics does the wrong thing and leads to more breakage. Defining the quirk and telling it exactly what to do is the safe and conservative approach. Signed-off-by: Oliver Neukum Cc: stable Link: https://patch.msgid.link/20260317084139.1461008-1-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/cdc-acm.c | 9 +++++++++ drivers/usb/class/cdc-acm.h | 1 + 2 files changed, 10 insertions(+) diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c index 7ede29d4c7c1..cf3c3eede1a5 100644 --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -1225,6 +1225,12 @@ static int acm_probe(struct usb_interface *intf, if (!data_interface || !control_interface) return -ENODEV; goto skip_normal_probe; + } else if (quirks == NO_UNION_12) { + data_interface = usb_ifnum_to_if(usb_dev, 2); + control_interface = usb_ifnum_to_if(usb_dev, 1); + if (!data_interface || !control_interface) + return -ENODEV; + goto skip_normal_probe; } /* normal probing*/ @@ -1748,6 +1754,9 @@ static const struct usb_device_id acm_ids[] = { { USB_DEVICE(0x045b, 0x024D), /* Renesas R-Car E3 USB Download mode */ .driver_info = DISABLE_ECHO, /* Don't echo banner */ }, + { USB_DEVICE(0x04b8, 0x0d12), /* EPSON HMD Com&Sens */ + .driver_info = NO_UNION_12, /* union descriptor is garbage */ + }, { USB_DEVICE(0x0e8d, 0x0003), /* FIREFLY, MediaTek Inc; andrey.arapov@gmail.com */ .driver_info = NO_UNION_NORMAL, /* has no union descriptor */ }, diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h index 76f73853a60b..25fd5329a878 100644 --- a/drivers/usb/class/cdc-acm.h +++ b/drivers/usb/class/cdc-acm.h @@ -114,3 +114,4 @@ struct acm { #define SEND_ZERO_PACKET BIT(6) #define DISABLE_ECHO BIT(7) #define MISSING_CAP_BRK BIT(8) +#define NO_UNION_12 BIT(9)