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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>
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