| From 811c926c538f7e8d3c08b630dd5844efd7e000f6 Mon Sep 17 00:00:00 2001 |
| From: Thomas Poussevin <thomas.poussevin@parrot.com> |
| Date: Thu, 27 Oct 2011 18:46:48 +0200 |
| Subject: USB: EHCI: fix HUB TT scheduling issue with iso transfer |
| |
| From: Thomas Poussevin <thomas.poussevin@parrot.com> |
| |
| commit 811c926c538f7e8d3c08b630dd5844efd7e000f6 upstream. |
| |
| 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: Matthieu Castet <matthieu.castet@parrot.com> |
| Signed-off-by: Thomas Poussevin <thomas.poussevin@parrot.com> |
| Signed-off-by: Alan Stern <stern@rowland.harvard.edu> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| drivers/usb/host/ehci-sched.c | 15 ++++++++++----- |
| 1 file changed, 10 insertions(+), 5 deletions(-) |
| |
| --- a/drivers/usb/host/ehci-sched.c |
| +++ b/drivers/usb/host/ehci-sched.c |
| @@ -1483,10 +1483,15 @@ iso_stream_schedule ( |
| |
| /* NOTE: assumes URB_ISO_ASAP, to limit complexity/bugs */ |
| |
| - /* find a uframe slot with enough bandwidth */ |
| - next = start + period; |
| - for (; start < next; start++) { |
| - |
| + /* find a uframe slot with enough bandwidth. |
| + * Early uframes are more precious because full-speed |
| + * 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? */ |
| if (stream->highspeed) { |
| if (itd_slot_ok(ehci, mod, start, |
| @@ -1499,7 +1504,7 @@ iso_stream_schedule ( |
| start, sched, period)) |
| break; |
| } |
| - } |
| + } while (start > next); |
| |
| /* no room in the schedule */ |
| if (start == next) { |
