From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pat LaVarre Subject: Re: [usb-storage] Re: [PATCH] fix Sony USB mass storage - pass larger receive buffer Date: 13 Nov 2003 19:10:34 -0700 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <1068775834.2851.321.camel@patrh9> References: <1068767049.2851.166.camel@patrh9> <1068768796.3fb41e1c8d075@webmail.netregistry.net> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from email-out1.iomega.com ([147.178.1.82]:34299 "EHLO email.iomega.com") by vger.kernel.org with ESMTP id S264488AbTKNCLG (ORCPT ); Thu, 13 Nov 2003 21:11:06 -0500 In-Reply-To: <1068768796.3fb41e1c8d075@webmail.netregistry.net> List-Id: linux-scsi@vger.kernel.org To: dmitrik@users.sourceforge.net Cc: usb-storage@one-eyed-alien.net, linux-scsi@vger.kernel.org, stern@rowland.harvard.edu, mdharm-scsi@one-eyed-alien.net, patmans@us.ibm.com, james.bottomley@steeleye.com, ronald@kuetemeier.com, idan@idanso.dyndns.org > * Define an absolute bare minimum safe subset of SCSI commands and > fall back to it whenever you see a non-compliant device like this one. Did we find a kind of reset that worked with this device? > Note that Win98 did not support my Sony Handycam Memory Stick out of > the box, I had to install drivers from Sony installation CD. > Obviously these drivers do not attempt to issue any commands that > the device does not understand. XP did detect Sony out of the box but > it is very likely that it still loaded proprietary Sony driver based > on USB Device/Vendor ID. I agree. I guess this from seeing bInterfaceSubClass = xFF = Formally Reserved But Informally Vendor Specific SCSI. That pushes the bInterfaceClass ...SubClass ...Protocol outside of the tuples that Microsoft blesses as generic usb storage i.e. outside of the set x 08 (02|05|06) 50. > Also note: the device does not claim any SCSI compliance as indicated > by reserved values in its device descriptor and by scsi version being > set to 0 in reply to INQUIRY. Aye. > IMHO the solution is either or both of: > * Blacklist it Can we blacklist mode sense from bInterfaceSubClass = xFF? That way we don't break as many write-protectable devices as if we blacklisted mode sense always? I remember today already I once proposed blacklisting only bInterfaceSubClass = xFF, Matt said no once, I don't think I yet grok Matt's no. Can we blacklist only xFF if I wrote the patch myself? I've shipped generic devices that I think comply: that gives me a personal interest in having their write-protect work, no matter if connected via USB. Pat LaVarre P.S. > Also note: the device does not claim any SCSI compliance... > miracle it worked at all. Aye. Myself, I'd like to get an academic grant to study why computers work. As far as I can tell, they shouldn't. Fundamentally chaotic design. Try flipping a bit in an instruction stream, and watch what happens.