Commit 8e04d805 authored Oct 01, 2010 by Hans de Goede Committed by Greg Kroah-Hartman Oct 22, 2010

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>

parent 319feaab

drivers/scsi/sr.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -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;
		}

include/scsi/scsi_device.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -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 */

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