hi Jiri: 2014-08-22 15:45 GMT+08:00 Jiri Kosina <jkosina@xxxxxxx>: > On Fri, 22 Aug 2014, CheChun Kuo wrote: > >> HID IR device will not response to any command send from host when >> it is finishing paring and tring to reset itself. During this period of >> time, usb_cleaer_halt will be fail and if hid_start_in soon again, we >> has the possibility trap in infinite loop. >> >> Signed-off-by: CheChun Kuo <vichy.kuo@xxxxxxxxx> >> --- >> drivers/hid/usbhid/hid-core.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c >> index 79cf503..256b102 100644 >> --- a/drivers/hid/usbhid/hid-core.c >> +++ b/drivers/hid/usbhid/hid-core.c >> @@ -122,7 +122,8 @@ static void hid_reset(struct work_struct *work) >> dev_dbg(&usbhid->intf->dev, "clear halt\n"); >> rc = usb_clear_halt(hid_to_usb_dev(hid), usbhid->urbin->pipe); >> clear_bit(HID_CLEAR_HALT, &usbhid->iofl); >> - hid_start_in(hid); >> + if (rc == 0) >> + hid_start_in(hid); >> } > > I'd need a more detailed explanation for this patch, as I don't understand > neither the text in the changelog nor the patch itself. Namely: > > - which IR devices are showing this behavior? The USB hid device that will transform IR signal to usb command when user press "volume up/down", "voice recording", etc. > - where does the infinite loop come from? hid_reset() should error out > properly if usb_clear_halt() fails and HID_IN_RUNNING flag is not set Below I briefly draw the timing when this issue happen i) hid_irq_in get URB status as -EPIPE ii) set HID_CLEAR_HALT flag and schedule hid_reset work iii) hid_reset call usb_clear_halt and hid_start_in again iv) if device still doesn't response host command, it will go to i) above and keep looping thanks for your help, -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
