[PATCH 1/2] scsi/sr: add no_read_disc_info scsi_device flag

[PATCH 1/2] scsi/sr: add no_read_disc_info scsi_device flag

[Hans de Goede]

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-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 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 d6f340f..dcd7069 100644
--- a/drivers/scsi/sr.c
+++ b/drivers/scsi/sr.c
@@ -848,10 +848,16 @@ 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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[PATCH 2/2] usb-storage: Add new no_read_disc_info quirk

[Hans de Goede]

Appotech ax3003 (the larger brother of the ax203) based devices are even
more buggy then the ax203. They will go of into lala land when ever they
see a READ_DISC_INFO scsi command. So add a new US_FL which tells the
scsi sr driver to not issue any READ_DISC_INFO scsi commands.

Signed-off-by: Hans de Goede <hdegoede-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
---
 drivers/usb/storage/scsiglue.c     |    4 ++++
 drivers/usb/storage/unusual_devs.h |    5 +++++
 include/linux/usb_usual.h          |    4 +++-
 3 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/drivers/usb/storage/scsiglue.c b/drivers/usb/storage/scsiglue.c
index 4cc0355..65d31f4 100644
--- a/drivers/usb/storage/scsiglue.c
+++ b/drivers/usb/storage/scsiglue.c
@@ -254,6 +254,10 @@ static int slave_configure(struct scsi_device *sdev)
 		 * or to force 192-byte transfer lengths for MODE SENSE.
 		 * But they do need to use MODE SENSE(10). */
 		sdev->use_10_for_ms = 1;
+
+		/* Some (fake) usb cdrom devices don't like READ_DISC_INFO */
+		if (us->fflags & US_FL_NO_READ_DISC_INFO)
+			sdev->no_read_disc_info = 1;
 	}
 
 	/* The CB and CBI transports have no way to pass LUN values
diff --git a/drivers/usb/storage/unusual_devs.h b/drivers/usb/storage/unusual_devs.h
index 391ccc8..56b3c08 100644
--- a/drivers/usb/storage/unusual_devs.h
+++ b/drivers/usb/storage/unusual_devs.h
@@ -1872,6 +1872,11 @@ UNUSUAL_DEV( 0x1908, 0x1320, 0x0000, 0x0000,
 		"Photo Frame",
 		US_SC_DEVICE, US_PR_DEVICE, NULL,
 		US_FL_BAD_SENSE ),
+UNUSUAL_DEV( 0x1908, 0x3335, 0x0200, 0x0200,
+		"BUILDWIN",
+		"Photo Frame",
+		US_SC_DEVICE, US_PR_DEVICE, NULL,
+		US_FL_NO_READ_DISC_INFO ),
 
 UNUSUAL_DEV( 0x2116, 0x0320, 0x0001, 0x0001,
 		"ST",
diff --git a/include/linux/usb_usual.h b/include/linux/usb_usual.h
index a4b947e..bff51d0 100644
--- a/include/linux/usb_usual.h
+++ b/include/linux/usb_usual.h
@@ -58,7 +58,9 @@
 	US_FLAG(CAPACITY_OK,	0x00010000)			\
 		/* READ CAPACITY response is correct */		\
 	US_FLAG(BAD_SENSE,	0x00020000)			\
-		/* Bad Sense (never more than 18 bytes) */
+		/* Bad Sense (never more than 18 bytes) */	\
+	US_FLAG(NO_READ_DISC_INFO,	0x00040000)		\
+		/* cannot handle READ_DISC_INFO */
 
 #define US_FLAG(name, value)	US_FL_##name = value ,
 enum { US_DO_ALL_FLAGS };
-- 
1.7.0.1

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