tree 70321ca66f373922bb722f81b315e08b510a826d
parent 48b4554aca28f721d3dfbab077c05032b3d1cd31
author Alan Stern <stern@rowland.harvard.edu> 1174413811 +0100
committer Jiri Kosina <jkosina@suse.cz> 1176280562 +0200

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>