Re: GetASF failed on DVD authentication

[Jens Axboe <axboe@suse.de>]

On Fri, Jan 02 2004, Jens Axboe wrote:
> On Fri, Jan 02 2004, Michael Hunold wrote:
> > Helloo
> > 
> > On 02.01.2004 15:25, Jeff Chua schrieb:
> > >On Fri, 2 Jan 2004, Jens Axboe wrote:
> > 
> > >USB drive is a Pioneer DVR-SK11B-J. It's reported as ...
> > >
> > >scsi0 : SCSI emulation for USB Mass Storage devices
> > >  Vendor: PIONEER   Model: DVD-RW  DVR-K11   Rev: 1.00
> > >  Type:   CD-ROM                             ANSI SCSI revision: 02
> > >
> > >I've tried at least 2 other USB drives (Plextor PX-208U, and Sony CRX85U),
> > >and both of these drives also exhibit the same problem.
> > 
> > >>>Linux version is 2.4.24-pre3.
> > 
> > >scsi0 : SCSI emulation for USB Mass Storage devices
> > >  Vendor: PIONEER   Model: DVD-RW  DVR-K11   Rev: 1.00
> > >  Type:   CD-ROM                             ANSI SCSI revision: 02
> > >Attached scsi CD-ROM sr0 at scsi0, channel 0, id 0, lun 0
> > >sr0: scsi-1 drive
> > 
> > IMHO the problem is inside SCSI drive recognition system, which can be 
> > found in "drivers/scsi/sr.c".
> > 
> > The function "get_capabilities()" tries to find out which type of drive 
> > you have.
> > 
> > ---------------------------schnipp--------------------------------------
> >     rc = sr_do_ioctl(i, cmd, buffer, 128, 1, SCSI_DATA_READ, NULL);
> > 
> >     if (rc) {
> >         /* failed, drive doesn't have capabilities mode page */
> >         scsi_CDs[i].cdi.speed = 1;
> >         scsi_CDs[i].cdi.mask |= (CDC_CD_R | CDC_CD_RW | CDC_DVD_R |
> >                      CDC_DVD | CDC_DVD_RAM |
> >                      CDC_SELECT_DISC | CDC_SELECT_SPEED);
> >         scsi_free(buffer, 512);
> >         printk("sr%i: scsi-1 drive\n", i);
> >         return;
> >     }
> > ---------------------------schnipp--------------------------------------
> > 
> > For my SCSI-2/USB drive, the above SCSI_DATA_READ command fails. As you 
> > can see, in this case the driver thinks that your drive is SCSI-1, ie. a 
> > CD-drive only. So DVD ioctls like the AGID commands will be filtered in 
> > the lower levels, because a CD-driver does not understand them anyway.
> > 
> > Unfortunately, the driver only knows SCSI-1 and SCSI-3, so SCSI-2 DVD 
> > driver are out of luck here and get downgraded to SCSI-1 CD-ROM stuff.
> > 
> > The patch below unmasks the DVD drive bit, ie. even if the kernel 
> > misdetects your driver, it will allow DVD ioctls to be passed to your drive.
> > 
> > This is not a safe fix, but "it works for me"(tm). I don't know how to 
> > really fix it; probably adding proper SCSI-2 support.
> > 
> > >Thanks,
> > >Jeff
> > 
> > CU
> > Michael.
> 
> > diff -ur linux-2.4.21/drivers/scsi/sr.c linux-2.4.21.patched/drivers/scsi/sr.c
> > --- linux-2.4.21/drivers/scsi/sr.c	2003-06-13 16:51:36.000000000 +0200
> > +++ linux-2.4.21.patched/drivers/scsi/sr.c	2003-08-27 23:52:32.000000000 +0200
> > @@ -725,7 +725,7 @@
> >  		/* failed, drive doesn't have capabilities mode page */
> >  		scsi_CDs[i].cdi.speed = 1;
> >  		scsi_CDs[i].cdi.mask |= (CDC_CD_R | CDC_CD_RW | CDC_DVD_R |
> > -					 CDC_DVD | CDC_DVD_RAM |
> > +					 /* USB-DVD-SCSI-2 hack: */ /* CDC_DVD | */  CDC_DVD_RAM |
> >  					 CDC_SELECT_DISC | CDC_SELECT_SPEED);
> >  		scsi_free(buffer, 512);
> >  		printk("sr%i: scsi-1 drive\n", i);
> 
> Better yet, kill the silly checks instead.

BTW Jeff, I'd still very much like to see the usb-storage log from when
sr gets loaded. Even though it's fine to kill the CDC_DVD checks, it
would still be a good idea to fix why the capabilities check fails. That
is the real bug.


-- 
Jens Axboe