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scsi/sr: add no_read_disc_info scsi_device flag 

Some USB devices emulate a usb-mass-storage attached (scsi) cdrom device,
usually this fake cdrom contains the windows software for the device.
While working on supporting Appotech ax3003 based photoframes, which do
this I discovered that they will go of into lala land when ever they see a
READ_DISC_INFO scsi command.

Thus this patch adds a scsi_device flag (which can then be set by the
usb-storage driver through an unsual-devs entry), to indicate this, and
makes the sr driver honor this flag.

I know this sucks, but as discussed on linux-scsi list there is no other
way to make this device work properly.

Looking at usb traces made under windows, windows never sends a
READ_DISC_INFO during normal interactions with a usb cdrom device.  So as
this cdrom emulation thingie becomes more common we might see more of this
problem.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Hans de Goede 2010-10-01 14:20:08 -07:00 committed by Greg Kroah-Hartman
parent 319feaabb6
commit 8e04d8056c
2 changed files with 8 additions and 1 deletions
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8
drivers/scsi/sr.c
View File

@ -862,10 +862,16 @@ static void get_capabilities(struct scsi_cd *cd)
static int sr_packet(struct cdrom_device_info *cdi,
struct packet_command *cgc)
{
struct scsi_cd *cd = cdi->handle;
struct scsi_device *sdev = cd->device;
if (cgc->cmd[0] == GPCMD_READ_DISC_INFO && sdev->no_read_disc_info)
return -EDRIVE_CANT_DO_THIS;
if (cgc->timeout <= 0)
cgc->timeout = IOCTL_TIMEOUT;
sr_do_ioctl(cdi->handle, cgc);
sr_do_ioctl(cd, cgc);
return cgc->stat;
}

1
include/scsi/scsi_device.h
View File

@ -148,6 +148,7 @@ struct scsi_device {
unsigned retry_hwerror:1; /* Retry HARDWARE_ERROR */
unsigned last_sector_bug:1; /* do not use multisector accesses on
SD_LAST_BUGGY_SECTORS */
unsigned no_read_disc_info:1; /* Avoid READ_DISC_INFO cmds */
unsigned is_visible:1; /* is the device visible in sysfs */
DECLARE_BITMAP(supported_events, SDEV_EVT_MAXBITS); /* supported events */