hi Jiri:

2014-08-22 15:45 GMT+08:00 Jiri Kosina [off-list ref]:

On Fri, 22 Aug 2014, CheChun Kuo wrote:

quoted

      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 <redacted>
---
 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,