From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alan Stern Subject: [ 12/16] USB: EHCI: fix bug in scheduling periodic split transfers Date: Thu, 7 Feb 2013 16:58:11 -0800 Message-Id: <20130208004629.261587402@linuxfoundation.org> In-Reply-To: <20130208004627.112511141@linuxfoundation.org> References: <20130208004627.112511141@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alan Stern commit 3e619d04159be54b3daa0b7036b0ce9e067f4b5d upstream. This patch (as1654) fixes a very old bug in ehci-hcd, connected with scheduling of periodic split transfers. The calculations for full/low-speed bus usage are all carried out after the correction for bit-stuffing has been applied, but the values in the max_tt_usecs array assume it hasn't been. The array should allow for allocation of up to 90% of the bus capacity, which is 900 us, not 780 us. The symptom caused by this bug is that any isochronous transfer to a full-speed device with a maxpacket size larger than about 980 bytes is always rejected with a -ENOSPC error. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- drivers/usb/host/ehci-sched.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/usb/host/ehci-sched.c +++ b/drivers/usb/host/ehci-sched.c @@ -236,7 +236,7 @@ static inline unsigned char tt_start_ufr } static const unsigned char -max_tt_usecs[] = { 125, 125, 125, 125, 125, 125, 30, 0 }; +max_tt_usecs[] = { 125, 125, 125, 125, 125, 125, 125, 25 }; /* carryover low/fullspeed bandwidth that crosses uframe boundries */ static inline void carryover_tt_bandwidth(unsigned short tt_usecs[8])