Commit 811c926c authored by Thomas Poussevin's avatar Thomas Poussevin Committed by Greg Kroah-Hartman

USB: EHCI: fix HUB TT scheduling issue with iso transfer

The current TT scheduling doesn't allow to play and then record on a
full-speed device connected to a high speed hub.

The IN iso stream can only start on the first uframe (0-2 for a 165 us)
because of CSPLIT transactions.
For the OUT iso stream there no such restriction. uframe 0-5 are possible.

The idea of this patch is that the first uframe are precious (for IN TT iso
stream) and we should allocate the last uframes first if possible.

For that we reverse the order of uframe allocation (last uframe first).

Here an example :

hid interrupt stream
----------------------------------------------------------------------
uframe                |  0  |  1  |  2  |  3  |  4  |  5  |  6  |  7  |
----------------------------------------------------------------------
max_tt_usecs          | 125 | 125 | 125 | 125 | 125 | 125 | 30  |  0  |
----------------------------------------------------------------------
used usecs on a frame | 13  |  0  |  0  |  0  |  0  |  0  |  0  |  0  |
----------------------------------------------------------------------

iso OUT stream
----------------------------------------------------------------------
uframe                |  0  |  1  |  2  |  3  |  4  |  5  |  6  |  7  |
----------------------------------------------------------------------
max_tt_usecs          | 125 | 125 | 125 | 125 | 125 | 125 | 30  |  0  |
----------------------------------------------------------------------
used usecs on a frame | 13  | 125 |  39 |  0  |  0  |  0  |  0  |  0  |
----------------------------------------------------------------------

There no place for iso IN stream  (uframe 0-2 are used) and we got "cannot
submit datapipe for urb 0, error -28: not enough bandwidth" error.

With the patch this become.

iso OUT stream
----------------------------------------------------------------------
uframe                |  0  |  1  |  2  |  3  |  4  |  5  |  6  |  7  |
----------------------------------------------------------------------
max_tt_usecs          | 125 | 125 | 125 | 125 | 125 | 125 | 30  |  0  |
----------------------------------------------------------------------
used usecs on a frame |  13 |  0  |  0  |  0  | 125 |  39 |  0  |  0  |
----------------------------------------------------------------------

iso IN stream
----------------------------------------------------------------------
uframe                |  0  |  1  |  2  |  3  |  4  |  5  |  6  |  7  |
----------------------------------------------------------------------
max_tt_usecs          | 125 | 125 | 125 | 125 | 125 | 125 | 30  |  0  |
----------------------------------------------------------------------
used usecs on a frame |  13 |  0  | 125 | 40  | 125 |  39 |  0  |  0  |
----------------------------------------------------------------------
Signed-off-by: default avatarMatthieu Castet <matthieu.castet@parrot.com>
Signed-off-by: default avatarThomas Poussevin <thomas.poussevin@parrot.com>
Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent f69e3120
...@@ -1479,10 +1479,15 @@ iso_stream_schedule ( ...@@ -1479,10 +1479,15 @@ iso_stream_schedule (
/* NOTE: assumes URB_ISO_ASAP, to limit complexity/bugs */ /* NOTE: assumes URB_ISO_ASAP, to limit complexity/bugs */
/* find a uframe slot with enough bandwidth */ /* find a uframe slot with enough bandwidth.
next = start + period; * Early uframes are more precious because full-speed
for (; start < next; start++) { * iso IN transfers can't use late uframes,
* and therefore they should be allocated last.
*/
next = start;
start += period;
do {
start--;
/* check schedule: enough space? */ /* check schedule: enough space? */
if (stream->highspeed) { if (stream->highspeed) {
if (itd_slot_ok(ehci, mod, start, if (itd_slot_ok(ehci, mod, start,
...@@ -1495,7 +1500,7 @@ iso_stream_schedule ( ...@@ -1495,7 +1500,7 @@ iso_stream_schedule (
start, sched, period)) start, sched, period))
break; break;
} }
} } while (start > next);
/* no room in the schedule */ /* no room in the schedule */
if (start == next) { if (start == next) {
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment