From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pat LaVarre Subject: Re: [PATCH] SCSI: limit mode sense usage Date: 29 Oct 2003 08:43:27 -0700 Sender: linux-scsi-owner@vger.kernel.org Message-ID: <1067442207.13824.3.camel@patehci2> References: Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Return-path: Received: from email-out1.iomega.com ([147.178.1.82]:18172 "EHLO email.iomega.com") by vger.kernel.org with ESMTP id S261850AbTJ2Pnm (ORCPT ); Wed, 29 Oct 2003 10:43:42 -0500 In-Reply-To: List-Id: linux-scsi@vger.kernel.org To: stern@rowland.harvard.edu Cc: ronald@kuetemeier.com, patmans@us.ibm.com, linux-scsi@vger.kernel.org, usb-storage@one-eyed-alien.net > > There now in -test9 I think I see: ... > > We guess writable if need be, but we prefer to settle for: ... > > sdkp->write_prot = ((data.device_specific & 0x80) != 0); ... > > after the first command that works in the sequence: ... > > sd_do_mode_sense(..., 0x3F, ..., 4, ...); > > sd_do_mode_sense(..., 0, buffer, 4, ...); > > sd_do_mode_sense(..., 0x3F, buffer, 255, ...); > > > > I mean to suggest, ... more closely ... Talk Like Windows ... > > e.g.: ... > > sd_do_mode_sense(..., 0x08, ..., 4, ...); > > There's an excellent reason for _not_ doing this, at least as far as > usb-storage is concerned. Namely, many USB Mass Storage devices die when > they receive MODE-SENSE(10) for page x08 but handle page x3F perfectly > well. Ronald's device is a rather unusual exception. Do these devices die for all lengths of op x5A MODE_SENSE_10 of page x08, or only for the rude, header-only, 4 or 8 byte length that we get by default if we patch drivers/scsi/ minimally? That is, do these devices die only when assaulted by: sd_do_mode_sense(..., 0x08, ..., 4, ...); in place of the more Windows-like: sd_do_mode_sense(..., 0x08, ..., 0x1C, ...); // if x5A MODE_SENSE_10 sd_do_mode_sense(..., 0x08, ..., 0x18, ...); // if x1A MODE_SENSE ? Pat LaVarre