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 <stern@rowland.harvard.edu>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/usbhid/hid-core.c b/drivers/hid/usbhid/hid-core.c
index 7c0fc11..35a41e6 100644
--- a/drivers/hid/usbhid/hid-core.c
+++ b/drivers/hid/usbhid/hid-core.c
@@ -554,6 +554,11 @@
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, ... */