kernel/drivers/usb/class/cdc-acm.h, branch 0x221E-v0.0.1-v6.19

cdc-acm: new quirk for EPSON HMD

2026-04-11T12:29:51Z

commit f97e96c303d689708f7f713d8f3afcc31f1237e9 upstream. 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

usb: cdc-acm: Restore CAP_BRK functionnality to CH343

2026-03-19T15:15:04Z

commit 14ae24cba291bddfdc296bbcbfd00cd09d0498ef upstream. The CH343 USB/serial adapter is as buggy as it is popular (very). One of its quirks is that despite being capable of signalling a BREAK condition, it doesn't advertise it. This used to work nonetheless until 66aad7d8d3ec5 ("usb: cdc-acm: return correct error code on unsupported break") applied some reasonable restrictions, preventing breaks from being emitted on devices that do not advertise CAP_BRK. Add a quirk for this particular device, so that breaks can still be produced on some of my machines attached to my console server. Fixes: 66aad7d8d3ec5 ("usb: cdc-acm: return correct error code on unsupported break") Signed-off-by: Marc Zyngier Cc: stable Cc: Oliver Neukum Cc: Greg Kroah-Hartman Acked-by: Oliver Neukum Link: https://patch.msgid.link/20260301124440.1192752-1-maz@kernel.org Signed-off-by: Greg Kroah-Hartman

USB: cdc-acm: use CDC serial-state defines

2022-07-25T08:57:41Z

Use the new CDC serial-state defines. Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20220725075841.1187-5-johan@kernel.org Signed-off-by: Greg Kroah-Hartman

USB: cdc-acm: use CDC control-line defines

2022-07-25T08:57:41Z

Use the new CDC control-line defines. Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20220725075841.1187-4-johan@kernel.org Signed-off-by: Greg Kroah-Hartman

tty: remove CMSPAR ifdefs

2022-05-19T16:26:16Z

CMSPAR is defined by all architectures since commit 6bf08cb246b5 ("[PATCH] Add CMSPAR to termbits.h for powerpc and alpha"). Reviewed-by: Johan Hovold Signed-off-by: Ilpo Järvinen Link: https://lore.kernel.org/r/20220513082906.11096-2-ilpo.jarvinen@linux.intel.com Signed-off-by: Greg Kroah-Hartman

USB: cdc-acm: fix minor-number release

2021-09-14T08:33:40Z

If the driver runs out of minor numbers it would release minor 0 and allow another device to claim the minor while still in use. Fortunately, registering the tty class device of the second device would fail (with a stack dump) due to the sysfs name collision so no memory is leaked. Fixes: cae2bc768d17 ("usb: cdc-acm: Decrement tty port's refcount if probe() fail") Cc: stable@vger.kernel.org # 4.19 Cc: Jaejoong Kim Acked-by: Oliver Neukum Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20210907082318.7757-1-johan@kernel.org Signed-off-by: Greg Kroah-Hartman

usb: cdc-acm: fix cooldown mechanism

2020-10-28T12:20:21Z

Commit a4e7279cd1d1 ("cdc-acm: introduce a cool down") is causing regression if there is some USB error, such as -EPROTO. This has been reported on some samples of the Odroid-N2 using the Combee II Zibgee USB dongle. > struct acm *acm = container_of(work, struct acm, work) is incorrect in case of a delayed work and causes warnings, usually from the workqueue: > WARNING: CPU: 0 PID: 0 at kernel/workqueue.c:1474 __queue_work+0x480/0x528. When this happens, USB eventually stops working completely after a while. Also the ACM_ERROR_DELAY bit is never set, so the cooldown mechanism previously introduced cannot be triggered and acm_submit_read_urb() is never called. This changes makes the cdc-acm driver use a single delayed work, fixing the pointer arithmetic in acm_softint() and set the ACM_ERROR_DELAY when the cooldown mechanism appear to be needed. Fixes: a4e7279cd1d1 ("cdc-acm: introduce a cool down") Cc: Oliver Neukum Reported-by: Pascal Vizeli Acked-by: Oliver Neukum Signed-off-by: Jerome Brunet Link: https://lore.kernel.org/r/20201019170702.150534-1-jbrunet@baylibre.com Cc: stable Signed-off-by: Greg Kroah-Hartman

USB: cdc-acm: clean up no-union-descriptor handling

2020-09-25T15:01:12Z

For interfaces that lack a union descriptor, probe for a "combined-interface" before falling back to the call-management descriptor instead of the other way round. This allows for the removal of the NO_DATA_INTERFACE quirk and makes the probe algorithm somewhat easier to follow. Acked-by: Oliver Neukum Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20200921135951.24045-5-johan@kernel.org Signed-off-by: Greg Kroah-Hartman

USB: cdc-acm: use common data-class define

2020-09-25T15:01:12Z

Use the data-class define provided by USB core and drop the driver-specific one. Acked-by: Oliver Neukum Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20200921135951.24045-4-johan@kernel.org Signed-off-by: Greg Kroah-Hartman

USB: cdc-acm: cleanup of data structures

2020-09-17T16:52:44Z

Buffers should be u8*, not unsigned char* Buffers have an unsigned length and using an int as a boolean is a bit outdated. No functional change intended. Signed-off-by: Oliver Neukum Link: https://lore.kernel.org/r/20200917110235.11854-1-oneukum@suse.com Signed-off-by: Greg Kroah-Hartman