From 1b9a38bfa6e664ff02511314f5586d711c83cc91 Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@rowland.harvard.edu>
Date: Fri, 8 Jan 2010 11:17:55 -0500
Subject: [PATCH] USB: EHCI: fix handling of unusual interrupt intervals
This patch (as1320) fixes two problems related to interrupt-URB
scheduling in ehci-hcd.
URBs with an interval of 2 or 4 microframes aren't handled.
For the time being, the patch reduces to interval to 1 uframe.
URBs are constrained to have an interval no larger than 1024
frames by usb_submit_urb(). But some EHCI controllers allow
use of a schedule as short as 256 frames; for these
controllers we may have to decrease the interval to the
actual schedule length.
The second problem isn't very significant since few devices expose
interrupt endpoints with an interval larger than 256 frames. But the
first problem is critical; it will prevent the kernel from working
with devices having interrupt intervals of 2 or 4 uframes.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Tested-by: Glynn Farrow <farrowg@sg.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
drivers/usb/host/ehci-q.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/host/ehci-q.c b/drivers/usb/host/ehci-q.c
index a427d3b00634..89521775c567 100644
--- a/drivers/usb/host/ehci-q.c
+++ b/drivers/usb/host/ehci-q.c
@@ -849,9 +849,10 @@ qh_make (
* But interval 1 scheduling is simpler, and
* includes high bandwidth.
*/
- dbg ("intr period %d uframes, NYET!",
- urb->interval);
- goto done;
+ urb->interval = 1;
+ } else if (qh->period > ehci->periodic_size) {
+ qh->period = ehci->periodic_size;
+ urb->interval = qh->period << 3;
}
} else {
int think_time;
@@ -874,6 +875,10 @@ qh_make (
usb_calc_bus_time (urb->dev->speed,
is_input, 0, max_packet (maxp)));
qh->period = urb->interval;
+ if (qh->period > ehci->periodic_size) {
+ qh->period = ehci->periodic_size;
+ urb->interval = qh->period;
+ }
}
}
--
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