This adds a workaround for an issue reported with ISO transfers
on some EHCI controllers, most recently with VIA KT800 and PS3
EHCI silicon.
The issue is that the silicon doesn't necessarily seem to be done
using ISO DMA descriptors (itd, sitd) when it marks them inactive.
(One theory is that the ill-defined mechanism where hardware caches
periodic transfer descriptors isn't invalidating their state...)
With such silicon, quick re-use of those descriptors makes trouble.
Waiting until the next frame seems to be a sufficient workaround.
This patch ensures that the relevant descriptors aren't available
for immediate re-use. It does so by not recycling them until after
issuing the completion callback which would reuse them by enqueueing
an URB and thus (re)allocating ISO DMA descriptors.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Acked-by: Geoff Levand <geoffrey.levand@am.sony.com>
Cc: Masashi Kimoto <Masashi_Kimoto@hq.scei.sony.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
30bf54e62a