On Fri, 2010-07-23 at 10:52 +0200, Hans de Goede wrote: > 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. So, I suppose we can do this. I dislike threading device bugs like this up and down the stack. The usb stor_control_thread already does some command filtering; if it just rejected this command and READ CAPACITY(16) on the flags, I think it would be far less code and the SCSI subsystem would just do the right thing. I'd actually like to hear from USB what they'd prefer to do. James -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
