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usbfs: Allow printer class 'get_device_id' without needing to claim the intf 

For certain (HP) printers the printer device_id does not only contain a
static part identifying the printer, but it also contains a dynamic part
giving printer status, ink level, etc.

To get to this info various userspace utilities need to be able to make a
printer class 'get_device_id' request without first claiming the interface
(as that is in use for the actual printer driver).

Since the printer class 'get_device_id' request does not change interface
settings in anyway, allowing this without claiming the interface should not
cause any issues.

CC: Sanjay Kumar <sanjay.kumar14@hp.com>
CC: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Hans de Goede 2013-07-12 10:04:18 +02:00 committed by Greg Kroah-Hartman
parent aaf6b52d50
commit 5dc50c357d
1 changed files with 3 additions and 3 deletions
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6
drivers/usb/core/devio.c
View File

@ -725,15 +725,15 @@ static int check_ctrlrecip(struct dev_state *ps, unsigned int requesttype,
/*
* check for the special corner case 'get_device_id' in the printer
* class specification, where wIndex is (interface << 8 | altsetting)
* instead of just interface
* class specification, which we always want to allow as it is used
* to query things like ink level, etc.
*/
if (requesttype == 0xa1 && request == 0) {
alt_setting = usb_find_alt_setting(ps->dev->actconfig,
index >> 8, index & 0xff);
if (alt_setting
&& alt_setting->desc.bInterfaceClass == USB_CLASS_PRINTER)
index >>= 8;
return 0;
}
index &= 0xff;