On Mon, 7 Sep 2009 17:09:32 +0200 Oliver Neukum <oliver@xxxxxxxxxx> wrote: > Am Montag, 7. September 2009 17:00:30 schrieb Alan Stern: > > On Mon, 7 Sep 2009, Oliver Neukum wrote: > > > Am Samstag, 5. September 2009 19:50:19 schrieb Paul Martin: > > > > cdc_acm: v0.26:USB Abstract Control Model driver for USB modems and > > > > ISDN adapters drivers/usb/class/cdc-acm.c: Entering acm_tty_open. > > > > drivers/usb/class/cdc-acm.c: acm_control_msg: rq: 0x22 val: 0x3 len: > > > > 0x0 result: 0 drivers/usb/class/cdc-acm.c: tty_port_block_til_ready > > > > returned -512 > > > > > > This is very hard to explain. I can't see how tty_port_block_til_ready() > > > can return -512 > > > Are you using any non-standard patches? > > > Alan, does this make sense to you?i > > I was actually referring to Alan Cox whom I had taken into cc. > Sorry for being unclear. There has been a change of Alan's for the USB serial stuff. I've also been away so I've not reviewed Alan Stern's latest patches. > > > No doubt it depends on which kernel is being used. In my kernel, for > > instance, tty_port_block_til_ready() will return -ERESTARTSYS in > > multiple places if a hangup or a signal occurs. > > Yes, but then it would work and user space knew it had to retry. > -512 simply does not look like a valid error return. I must be even > denser than usual. One thing to check is if the app sets a timer and calls open which for some reason then doesn't see a carrier signal being raised if clocal is not set. If clocal is not set by default on acm ports we can certainly set clocal in the initial port setup if its causing a regression due to a dumb app not coping with working POSIX compliance. Alan -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
