Re: long-term regression with some usb mass storage devices

[Alan Stern]

On Fri, 20 Feb 2009, Mike Lampard wrote:

> On Fri, 20 Feb 2009 05:17:42 pm Mike Lampard wrote:
> > Hi All,
> >
> > I recently plonked a dvd into my usb-attached Pioneer DVR-107d only to find
> > that the current kernels no longer saw the drive as DVD capable.  In fact,
> > the kernel no longer saw _any_ features of the drive: sr0: scsi3-mmc drive:
> > 0x/0x caddy.  After much bisecting and even more blind luck I narrowed the
> > problem down to this commit:
> >
> > commit bdb2b8cab4392ce41ddfbd6773a3da3334daf836
> > Author: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> > Date:   Tue Jun 24 14:03:14 2008 -0400
> >
> >     [SCSI] erase invalid data returned by device
> >
> >     This patch (as1108) fixes a problem that can occur with certain USB
> >     mass-storage devices: They return invalid data together with a residue
> >     indicating that the data should be ignored.  Rather than leave the
> >     invalid data in a transfer buffer, where it can get misinterpreted,
> >     the patch clears the invalid portion of the buffer.
> >
> >     This solves a problem (wrong write-protect setting detected) reported
> >     by Maciej Rutecki and Peter Teoh.

If this affected your device then the device must not report residues 
correctly.  If you provide the device's entry in /proc/bus/usb/devices, 
I'll write a patch adding a blacklist entry for it.

It would help if you could also provide a usbmon trace showing what 
happens when you plug the drive in.  Instructions are in the kernel 
source file Documentation/usb/usbmon.txt.

Alan Stern

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