Re: [usb-storage] Re: [PATCH] fix Sony USB mass storage - pass larger receive buffer

Matthew Dharm
2003-11-13T19:14:40Z

[-- Attachment #1: Type: text/plain, Size: 1746 bytes --]

On Thu, Nov 13, 2003 at 11:37:09AM -0700, Pat LaVarre wrote:
> > > How about we blacklist all the bInterfaceSubClass that Windows does not
> > > regard as generic. I remember Windows does regard bInterfaceSubClass =
> > > x06 as generic. I think I remember there are two others.
> >
> > grep -i generic
> > in windows/inf/usbstor.inf yields, hex:
> >
> > 08 02 50
> > 08 05 50
> > 08 06 50
> >
> > How about we [guess] disk writable
> > [without risking mode sense]
> > if we do not find bInterfaceSubClass in
> > the set x 02 05 06?
>
> In short:
>
> Or how about we only blacklist mode sense from devices that report
> bInterfaceSubClass = any of the x07..FF Reserved codes? Surely a device
> sending us a formally Reserved code is a good first clue that it may not
> behave robustly thereafter? Or maybe we just blacklist mode sense from
> bInterfaceSubClass = xFF FormallyReservedButInformallyVendorSpecific?
> Surely a device sending us that code is an even better first clue that
> it may not behave robustly thereafter?

Our experience tells us that xFF is often used because designers are one of
the following:
(a) lazy
(b) incompetient
(c) driven by marketing, which wants to load an .inf so their
device seems 'special' (custom icons, etc.)

So xFF doesn't really tell us, deterministically, anything at all.

Knowing that the device is direct-access, however, implies very strongly
that MODE_SENSE[_10] is a bad idea.

Matt

--
Matthew Dharm Home: mdharm-usb@one-eyed-alien.net
Maintainer, Linux USB Mass Storage Driver

Okay, this isn't funny anymore! Let me down! I'll tell Bill on you!!
-- Microsoft Salesman
User Friendly, 4/1/1998

[-- Attachment #2: Type: application/pgp-signature, Size: 232 bytes --]