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@xxxxxxxxxx>
---
drivers/scsi/sr.c | 8 +++++++-
include/scsi/scsi_device.h | 1 +
2 files changed, 8 insertions(+), 1 deletions(-)
diff --git a/drivers/scsi/sr.c b/drivers/scsi/sr.c
index 0a90abc..18077b5 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -849,10 +849,16 @@ 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;
}
diff --git a/include/scsi/scsi_device.h b/include/scsi/scsi_device.h
index d80b6db..e1b2db8 100644
--- a/include/scsi/scsi_device.h
+++ b/include/scsi/scsi_device.h
@@ -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 */
--
1.7.0.1
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