kernel_optimize_test/drivers/usb/wusbcore/pal.c
Thomas Pugliese a899575191 USB: HWA: fix device probe failure
This patch fixes a race condition that caused the HWA_HC interface probe
function to occasionally fail.  The HWA_HC would attempt to register
itself with the HWA_RC by searching for a uwb_rc class device with the
same parent device ptr.  If the probe function for the HWA_RC interface
had yet to run, the uwb_rc class device would not have been created
causing the look up to fail and the HWA_HC probe function to return an
error causing the device to be unusable.

The fix is for the HWA to delay registering with the HWA_RC until
receiving the command from userspace to start the wireless channel.  It
is the responsibility of userspace to ensure that the uwb_rc class
device has been created before starting the HWA channel.

Signed-off-by: Thomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-06-24 16:20:43 -07:00

56 lines
1.5 KiB
C

/*
* Wireless USB Host Controller
* UWB Protocol Adaptation Layer (PAL) glue.
*
* Copyright (C) 2008 Cambridge Silicon Radio Ltd.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "wusbhc.h"
static void wusbhc_channel_changed(struct uwb_pal *pal, int channel)
{
struct wusbhc *wusbhc = container_of(pal, struct wusbhc, pal);
if (channel < 0)
wusbhc_stop(wusbhc);
else
wusbhc_start(wusbhc);
}
/**
* wusbhc_pal_register - register the WUSB HC as a UWB PAL
* @wusbhc: the WUSB HC
*/
int wusbhc_pal_register(struct wusbhc *wusbhc)
{
uwb_pal_init(&wusbhc->pal);
wusbhc->pal.name = "wusbhc";
wusbhc->pal.device = wusbhc->usb_hcd.self.controller;
wusbhc->pal.rc = wusbhc->uwb_rc;
wusbhc->pal.channel_changed = wusbhc_channel_changed;
return uwb_pal_register(&wusbhc->pal);
}
/**
* wusbhc_pal_unregister - unregister the WUSB HC as a UWB PAL
* @wusbhc: the WUSB HC
*/
void wusbhc_pal_unregister(struct wusbhc *wusbhc)
{
if (wusbhc->uwb_rc)
uwb_pal_unregister(&wusbhc->pal);
}