linux-kernel - Re: PROBLEM: USB ACM device does not work

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Pine.LNX.4.44L0.0906301656440.5222-100000@iolanthe.rowland.org>
Date:	Tue, 30 Jun 2009 17:01:00 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Arseniy Lartsev <ars3n@...dex.ru>
cc:	Oliver Neukum <oliver@...kum.org>,
	USB list <linux-usb@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: PROBLEM: USB ACM device does not work

On Wed, 1 Jul 2009, Arseniy Lartsev wrote:

> On Tuesday 30 June 2009 11:22:04 Oliver Neukum wrote:
> > Yet, your device shows bulk endpoints. Please enable DEBUG in cdc-acm.c
> > and recompile with CONFIG_USB_DEBUG.
> 
> I've recompiled four modules usbcore, ehci_hcd, ohci_hcd and cdc-acm with -DDEBUG.
> Here is kernel log:
> 
> ======================== Device plugged in ========================
...
> Jun 30 23:58:35 noteb00k kernel: usb 2-3: new low speed USB device using ohci_hcd and address 5                        
...
> Jun 30 23:58:35 noteb00k kernel: usb 2-3: config 1 interface 1 altsetting 0 endpoint 0x1 is Bulk; changing to 
> Interrupt
> Jun 30 23:58:35 noteb00k kernel: usb 2-3: config 1 interface 1 altsetting 0 endpoint 0x81 is Bulk; changing to 
> Interrupt                                                                                                                      

This looks like your problem.  Low-speed devices are not allowed to 
have bulk endpoints.  Linux internally changes them to interrupt 
endpoints with interval = 1 and maxpacket size no larger than 8.

Alan Stern

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/