[PATCH] improved TT scheduling for EHCI
This updates the EHCI driver by adding an improved scheduler for the
transaction translators, found in USB 2.0 hubs and used for low and
full speed devices.
- adds periodic_tt_usecs() and some helper functions, which does
the same thing that "periodic_usecs" does, except on the other
side of the TT, i.e. it calculates the low/fullspeed bandwidth
usage instead of highspeed.
- adds a tt_available() function which is the new implementation
of what tt_no_collision() does ... while tt_no_collision() ensures
that each TT handles only 1 periodic transfer at a time (a very
pessimistic approach) this version instead tracks bandwidth and
allows each TT to handle as many transfers as will fit on each TT's
downstream bus (closer to best-case).
The new scheduler is selected by a config option, marked as EXPERIMENTAL
so it can be tested (and more broadly reviewed) for a while until it
seems safe to remove the original scheduler.
Signed-off-by: Dan Streetman <ddstreet@ieee.org>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2 files changed