Package: linux-image-amd64
Version: 6.12.57-1
Severity: normal
Tags: patch
X-Debbugs-Cc: [email protected]
User: [email protected]
Usertags: amd64
Dear Maintainer,
I propose a patch to workaround USB HID descriptor requirements that are
stopping users from being able to use astrophotography equipment.
I have a usb device (an ZWO EFWmini, used for astronomy) which has the
following vendor information: 03c3:1f01 ZWO ZWO EFW
This device is known to offer a suboptimal descriptor, e.g. see the lsusb output
Warning: Descriptor too short
HID Device Descriptor:
bLength 9
bDescriptorType 33
bcdHID 1.01
bCountryCode 0 Not supported
bNumDescriptors 2
bDescriptorType 34 (null)
wDescriptorLength 68
bDescriptorType 0 (null)
wDescriptorLength 0
Report Descriptors:
** UNAVAILABLE **
My software (I write it, it is GPLv3, I'm the only user, but it isn't
particularly relevant...) runs primarilly on a raspberry pi, which accepts this
with kernel 6.12.25-1+rpt1, and I've also done some desktop development on
archlinux (unknown kernel versions but up to at least 6 months ago). I only
access the hardware for development from a debian desktop computer.
Since moving to Debian 13, my hardware no longer works, with dmesg showing the
following error:
[ 14.182522] usb 1-2.2: new full-speed USB device number 10 using xhci_hcd
[ 14.276921] usb 1-2.2: New USB device found, idVendor=03c3, idProduct=1f01,
bcdDevice= 0.00
[ 14.276930] usb 1-2.2: New USB device strings: Mfr=1, Product=2,
SerialNumber=0
[ 14.276933] usb 1-2.2: Product: ZWO EFW
[ 14.276935] usb 1-2.2: Manufacturer: ZW0
[ 14.282951] usbhid 1-2.2:1.0: can't add hid device: -22
[ 14.282963] usbhid 1-2.2:1.0: probe with driver usbhid failed with error -22
I have tried going back as far as debian's kernel from bullseye (5.10),
bookworm (6.1), trixie (6.12) and backports (6.17) but it's the same error
every time.
Communicating with the ZWO (the device manufacturer) support team, they
recommended patching the kernel, which I did, and it now works.
I applied the following patch and built my own kernel
===========================================================================
--- drivers/hid/usbhid/hid-core.c.orig 2025-12-08 13:15:08.657917762 +0000
+++ drivers/hid/usbhid/hid-core.c 2025-12-08 13:16:24.293959487 +0000
@@ -1015,7 +1015,7 @@
(hdesc->bNumDescriptors - 1) * sizeof(*hcdesc)) {
dbg_hid("hid descriptor invalid, bLen=%hhu bNum=%hhu\n",
hdesc->bLength, hdesc->bNumDescriptors);
- return -EINVAL;
+ // return -EINVAL;
}
hid->version = le16_to_cpu(hdesc->bcdHID);
===========================================================================
The new dmesg output is
[ 366.477628] usbhid 1-2:1.0: 1 unsupported optional hid class descriptors
[ 366.478327] hid-generic 0003:03C3:1F01.0006: hiddev1,hidraw4: USB HID v1.01
Device [ZW0 ZWO EFW] on usb-000
Apologies but I don't think I'm giving you a particularly good patch because
the author of this code clearly intended for a -EINVAL failure. A kernel dev
may prefer to create a hardware quirk (which ideally should be enabled for
03c3:1f01 by default) to exit if the descriptor isn't valid. I'm not a kernel
developer so that's beyond me.
The device works perfectly fine despite the descriptor not meeting the kernel's
current requirements. And I don't believe a firmware upgrade is possible...
it's just a little motor that turns a wheel containing photographic filters.
-- System Information:
Debian Release: 13.2
APT prefers stable-updates
APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable')
Architecture: amd64 (x86_64)
Kernel: Linux 6.12+unreleased-amd64 (SMP w/28 CPU threads; PREEMPT)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8),
LANGUAGE=en_GB:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled
Versions of packages linux-image-amd64 depends on:
ii linux-image-6.12.57+deb13-amd64 6.12.57-1
linux-image-amd64 recommends no packages.
linux-image-amd64 suggests no packages.
-- no debconf information
