linux/drivers/net/wireless/wl1251/ps.c
Grazvydas Ignotas 5f6722ee63 wl1251: fix elp_work race condition
While working on PS I've noticed elp_work is kicking rather often, and
sometimes the chip is put to sleep before 5ms delay expires. This
seems to happen because by the time wl1251_ps_elp_wakeup is called
elp_work might still be pending. After wakeup is done, the processing
may take some time, during which 5ms might expire and elp_work might
get scheduled. In this case, ss soon as 1st thread finishes work and
releases the mutex, elp_work will then put the device to sleep without
5ms delay. In addition 1st thread will queue additional elp_work
needlessly.

Fix this by cancelling work in wl1251_ps_elp_wakeup instead.

Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Acked-by: Kalle Valo <kvalo@adurom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
2011-03-11 14:15:35 -05:00

177 lines
3.9 KiB
C

/*
* This file is part of wl1251
*
* Copyright (C) 2008 Nokia Corporation
*
* 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, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA
*
*/
#include "reg.h"
#include "ps.h"
#include "cmd.h"
#include "io.h"
/* in ms */
#define WL1251_WAKEUP_TIMEOUT 100
void wl1251_elp_work(struct work_struct *work)
{
struct delayed_work *dwork;
struct wl1251 *wl;
dwork = container_of(work, struct delayed_work, work);
wl = container_of(dwork, struct wl1251, elp_work);
wl1251_debug(DEBUG_PSM, "elp work");
mutex_lock(&wl->mutex);
if (wl->elp || !wl->psm)
goto out;
wl1251_debug(DEBUG_PSM, "chip to elp");
wl1251_write_elp(wl, HW_ACCESS_ELP_CTRL_REG_ADDR, ELPCTRL_SLEEP);
wl->elp = true;
out:
mutex_unlock(&wl->mutex);
}
#define ELP_ENTRY_DELAY 5
/* Routines to toggle sleep mode while in ELP */
void wl1251_ps_elp_sleep(struct wl1251 *wl)
{
unsigned long delay;
if (wl->psm) {
delay = msecs_to_jiffies(ELP_ENTRY_DELAY);
ieee80211_queue_delayed_work(wl->hw, &wl->elp_work, delay);
}
}
int wl1251_ps_elp_wakeup(struct wl1251 *wl)
{
unsigned long timeout, start;
u32 elp_reg;
if (delayed_work_pending(&wl->elp_work))
cancel_delayed_work(&wl->elp_work);
if (!wl->elp)
return 0;
wl1251_debug(DEBUG_PSM, "waking up chip from elp");
start = jiffies;
timeout = jiffies + msecs_to_jiffies(WL1251_WAKEUP_TIMEOUT);
wl1251_write_elp(wl, HW_ACCESS_ELP_CTRL_REG_ADDR, ELPCTRL_WAKE_UP);
elp_reg = wl1251_read_elp(wl, HW_ACCESS_ELP_CTRL_REG_ADDR);
/*
* FIXME: we should wait for irq from chip but, as a temporary
* solution to simplify locking, let's poll instead
*/
while (!(elp_reg & ELPCTRL_WLAN_READY)) {
if (time_after(jiffies, timeout)) {
wl1251_error("elp wakeup timeout");
return -ETIMEDOUT;
}
msleep(1);
elp_reg = wl1251_read_elp(wl, HW_ACCESS_ELP_CTRL_REG_ADDR);
}
wl1251_debug(DEBUG_PSM, "wakeup time: %u ms",
jiffies_to_msecs(jiffies - start));
wl->elp = false;
return 0;
}
int wl1251_ps_set_mode(struct wl1251 *wl, enum wl1251_cmd_ps_mode mode)
{
int ret;
switch (mode) {
case STATION_POWER_SAVE_MODE:
wl1251_debug(DEBUG_PSM, "entering psm");
/* enable beacon filtering */
ret = wl1251_acx_beacon_filter_opt(wl, true);
if (ret < 0)
return ret;
ret = wl1251_acx_wake_up_conditions(wl,
WAKE_UP_EVENT_DTIM_BITMAP,
wl->listen_int);
if (ret < 0)
return ret;
ret = wl1251_acx_bet_enable(wl, WL1251_ACX_BET_ENABLE,
WL1251_DEFAULT_BET_CONSECUTIVE);
if (ret < 0)
return ret;
ret = wl1251_cmd_ps_mode(wl, STATION_POWER_SAVE_MODE);
if (ret < 0)
return ret;
ret = wl1251_acx_sleep_auth(wl, WL1251_PSM_ELP);
if (ret < 0)
return ret;
wl->psm = 1;
break;
case STATION_ACTIVE_MODE:
default:
wl1251_debug(DEBUG_PSM, "leaving psm");
ret = wl1251_acx_sleep_auth(wl, WL1251_PSM_CAM);
if (ret < 0)
return ret;
/* disable BET */
ret = wl1251_acx_bet_enable(wl, WL1251_ACX_BET_DISABLE,
WL1251_DEFAULT_BET_CONSECUTIVE);
if (ret < 0)
return ret;
/* disable beacon filtering */
ret = wl1251_acx_beacon_filter_opt(wl, false);
if (ret < 0)
return ret;
ret = wl1251_acx_wake_up_conditions(wl,
WAKE_UP_EVENT_DTIM_BITMAP,
wl->listen_int);
if (ret < 0)
return ret;
ret = wl1251_cmd_ps_mode(wl, STATION_ACTIVE_MODE);
if (ret < 0)
return ret;
wl->psm = 0;
break;
}
return ret;
}