Re: [PATCH 7/8] don't mangle INQUIRY if cmddt or evpd bits are set

[Stefan Richter <stefanr@s5r6.in-berlin.de>]

Al Viro wrote:
> On Mon, Feb 13, 2006 at 05:19:55PM +0100, Stefan Richter wrote:
> > BTW, a Prolific based enclosure indeed seems to be unable to handle
> > CD-ROMs after scsiinfo treatment. An enclosure based on an old
> > revision of TI StorageLynx apparently causes mode_sense -> check
> > condition/ unit attention loops when scsiinfo tries to access some
> > mode page.
>
> The former is best treated by using the hardware in question as a pissuary,
> to make sure that its contents matches the quality of design.

I have got the impression that most of IEEE 1394a/ USB 2.0 combo bridges 
on the market are now based on Prolific chips.

> The latter
> might be more interesting - RBC devices are only required to implement
> MODE SENSE/SELECT page 6; they shouldn't get messed by the rest, but at
> least some of them blindly respond with page 6 to _every_ MODE SENSE.
> So that might be a good reason to blacklist.

Some more findings:
 - The TI StorageLynx based bridge reports device type 0 (TYPE_DISK).
   The problem occurs apparently with page 4 and page 8. Sbp2 has a
   fix since yesterday which sets the skip_ms_page_8 flag.
   http://marc.theaimsgroup.com/?l=linux1394-devel&m=113969287630893
 - Another bridge made by the same manufacturer but based on TI
   StorageLynx revision A features the same MODE SENSE bug. This bridge
   reports type 14 (TYPE_RBC).
 - I tested a tenth bridge now, based on Initio INIC-2430F. The bridge
   reports TYPE_DISK and seems to support all pages which scsiinfo is
   interested in. Sd_mod is a different story: After sd_mod accesses
   page 8, the kernel panics. (This is discussed in another thread. The
   mentioned sbp2 patch catches this bridge as a skip_ms_page_8
   candidate too, thus avoids the panic. I will eventually check what
   sd_mod is doing; the sbp2 patch is not the real fix.)

Of course sg does not care for any black list flags (like sd_mod and 
sr_mod do), but considering the nature of the bugs and anticipated usage 
of affected devices, there is hardly a reason for further safeguards in 
sbp2, let alone sg.
--
Stefan Richter
-=====-=-==- --=- -==-=
http://arcgraph.de/sr/
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