From 5e2a55f25d255a356bdaf2cb04c71b8d76c307a8 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Tue, 20 Mar 2007 19:03:31 +0100 Subject: [PATCH] USB HID: fix retry & reset logic The USB HID driver fails to reset its error-retry timeout when there has been a long time interval between I/O errors with no successful URB completions in the meantime. As a result, the very next error would trigger an immediate reset, even if it was a chance event occurring long after the previous error. More USB keyboards and mice than one might expect end up getting I/O errors. Almost always this results from hardware problems of one sort of another. For example, people attach the device to a USB extension cable, which degrades the signal. Or they simply have poor quality cables to begin with. Or they use a KVM switch which doesn't handle USB messages correctly. Etc... There have been reports from several users in which these I/O errors would occur more or less randomly, at intervals ranging from seconds to minutes. The error-handling code in hid-core.c was originally meant for situations where a single outage would persist for a few hundred ms (electromagnetic interference, for example). It didn't work right when these more sporadic errors occurred, because of a flaw in the logic which this patch fixes. This patch (as873) fixes that oversight. Signed-off-by: Alan Stern Signed-off-by: Jiri Kosina --- drivers/hid/usbhid/hid-core.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c index 7c0fc11e972a..35a41e60f541 100644 --- a/drivers/hid/usbhid/hid-core.c +++ b/drivers/hid/usbhid/hid-core.c @@ -554,6 +554,11 @@ static void hid_io_error(struct hid_device *hid) if (usb_get_intfdata(usbhid->intf) == NULL) goto done; + /* If it has been a while since the last error, we'll assume + * this a brand new error and reset the retry timeout. */ + if (time_after(jiffies, usbhid->stop_retry + HZ/2)) + usbhid->retry_delay = 0; + /* When an error occurs, retry at increasing intervals */ if (usbhid->retry_delay == 0) { usbhid->retry_delay = 13; /* Then 26, 52, 104, 104, ... */ -- 2.20.1