From: Hans de Goede Date: Fri, 12 Jul 2013 08:04:18 +0000 (+0200) Subject: usbfs: Allow printer class 'get_device_id' without needing to claim the intf X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=5dc50c357d5ce8f78e148d20a38e4e66b12d550f;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git 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 CC: Alan Stern Signed-off-by: Hans de Goede Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/usb/core/devio.c b/drivers/usb/core/devio.c index 05986507b585..737e3c19967b 100644 --- a/drivers/usb/core/devio.c +++ b/drivers/usb/core/devio.c @@ -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;