tree 0f364e86f1e89a74020d024516560de474740c71
parent 7eede2cbc1066124a0a4fee4d9671e28f7c62277
author Alan Stern <stern@rowland.harvard.edu> 1318430354 -0400
committer Greg Kroah-Hartman <gregkh@suse.de> 1321032917 -0800

EHCI: workaround for MosChip controller bug

commit 68aa95d5d4de31c9348c1628ffa85c805305ebc5 upstream.

This patch (as1489) works around a hardware bug in MosChip EHCI
controllers.  Evidently when one of these controllers increments the
frame-index register, it changes the three low-order bits (the
microframe counter) before changing the higher order bits (the frame
counter).  If the register is read at just the wrong time, the value
obtained is too low by 8.

When the appropriate quirk flag is set, we work around this problem by
reading the frame-index register a second time if the first value's
three low-order bits are all 0.  This gives the hardware a chance to
finish updating the register, yielding the correct value.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Tested-by: Jason N Pitt <jpitt@fhcrc.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>