This is a note to let you know that I've just added the patch titled
USB: revert periodic scheduling bugfix
to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From fdc03438f53a00294ed9939eb3a1f6db6f3d8963 Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Date: Tue, 28 May 2013 14:03:10 -0400
Subject: USB: revert periodic scheduling bugfix
This patch reverts commit 3e619d04159be54b3daa0b7036b0ce9e067f4b5d
(USB: EHCI: fix bug in scheduling periodic split transfers). The
commit was valid -- it fixed a real bug -- but the periodic scheduler
in ehci-hcd is in such bad shape (especially the part that handles
split transactions) that fixing one bug is very likely to cause
another to surface. That's what happened in this case; the result was
choppy and noisy playback on certain 24-bit audio devices.
The only real fix will be to rewrite this entire section of code. My
next project...
This fixes https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1136110.
Thanks to Tim Richardson for extra testing and feedback, and to Joseph
Salisbury and Tyson Tan for tracking down the original source of the
problem.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
CC: Joseph Salisbury <joseph.salisbury@xxxxxxxxxxxxx>
CC: Tim Richardson <tim@xxxxxxxxxxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/host/ehci-sched.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/usb/host/ehci-sched.c b/drivers/usb/host/ehci-sched.c
index acff5b8..f3c1028 100644
--- a/drivers/usb/host/ehci-sched.c
+++ b/drivers/usb/host/ehci-sched.c
@@ -213,7 +213,7 @@ static inline unsigned char tt_start_uframe(struct ehci_hcd *ehci, __hc32 mask)
}
static const unsigned char
-max_tt_usecs[] = { 125, 125, 125, 125, 125, 125, 125, 25 };
+max_tt_usecs[] = { 125, 125, 125, 125, 125, 125, 30, 0 };
/* carryover low/fullspeed bandwidth that crosses uframe boundries */
static inline void carryover_tt_bandwidth(unsigned short tt_usecs[8])
--
1.8.3.rc1.46.g4a27aed
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