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wl1271: Fix queue stopping/waking for TX path

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The queue stopping/waking functionality was broken in a way that could
cause huge latencies in TX transfers and even cause the TX to stall in the
right circumstances. Correct these problems.

Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Reviewed-by: Kalle Valo <kalle.valo@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
This commit is contained in:
Juuso Oikarinen 2010-02-22 08:38:33 +02:00 committed by John W. Linville
parent 15305498a4
commit 06f7bc7db7
3 changed files with 22 additions and 21 deletions
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3
drivers/net/wireless/wl12xx/wl1271.h
View File

@ -491,7 +491,8 @@ int wl1271_plt_stop(struct wl1271 *wl);
#define WL1271_DEFAULT_POWER_LEVEL 0
#define WL1271_TX_QUEUE_MAX_LENGTH 20
#define WL1271_TX_QUEUE_LOW_WATERMARK 10
#define WL1271_TX_QUEUE_HIGH_WATERMARK 25
/* WL1271 needs a 200ms sleep after power on, and a 20ms sleep before power
on in case is has been shut down shortly before */

12
drivers/net/wireless/wl12xx/wl1271_main.c
View File

@ -791,15 +791,13 @@ static int wl1271_op_tx(struct ieee80211_hw *hw, struct sk_buff *skb)
* The workqueue is slow to process the tx_queue and we need stop
* the queue here, otherwise the queue will get too long.
*/
if (skb_queue_len(&wl->tx_queue) >= WL1271_TX_QUEUE_MAX_LENGTH) {
ieee80211_stop_queues(wl->hw);
if (skb_queue_len(&wl->tx_queue) >= WL1271_TX_QUEUE_HIGH_WATERMARK) {
wl1271_debug(DEBUG_TX, "op_tx: stopping queues");
/*
* FIXME: this is racy, the variable is not properly
* protected. Maybe fix this by removing the stupid
* variable altogether and checking the real queue state?
*/
spin_lock_irqsave(&wl->wl_lock, flags);
ieee80211_stop_queues(wl->hw);
set_bit(WL1271_FLAG_TX_QUEUE_STOPPED, &wl->flags);
spin_unlock_irqrestore(&wl->wl_lock, flags);
}
return NETDEV_TX_OK;

28
drivers/net/wireless/wl12xx/wl1271_tx.c
View File

@ -278,22 +278,12 @@ void wl1271_tx_work(struct work_struct *work)
ret = wl1271_tx_frame(wl, skb);
if (ret == -EBUSY) {
/* firmware buffer is full, stop queues */
wl1271_debug(DEBUG_TX, "tx_work: fw buffer full, "
"stop queues");
ieee80211_stop_queues(wl->hw);
set_bit(WL1271_FLAG_TX_QUEUE_STOPPED, &wl->flags);
/* firmware buffer is full, lets stop transmitting. */
skb_queue_head(&wl->tx_queue, skb);
goto out_ack;
} else if (ret < 0) {
dev_kfree_skb(skb);
goto out_ack;
} else if (test_and_clear_bit(WL1271_FLAG_TX_QUEUE_STOPPED,
&wl->flags)) {
/* firmware buffer has space, restart queues */
wl1271_debug(DEBUG_TX,
"complete_packet: waking queues");
ieee80211_wake_queues(wl->hw);
}
}
@ -380,8 +370,6 @@ void wl1271_tx_complete(struct wl1271 *wl)
u32 count, fw_counter;
u32 i;
wl1271_debug(DEBUG_TX, "tx_complete received, packets: %d", count);
/* read the tx results from the chipset */
wl1271_read(wl, le32_to_cpu(memmap->tx_result),
wl->tx_res_if, sizeof(*wl->tx_res_if), false);
@ -393,6 +381,7 @@ void wl1271_tx_complete(struct wl1271 *wl)
tx_result_host_counter), fw_counter);
count = fw_counter - wl->tx_results_count;
wl1271_debug(DEBUG_TX, "tx_complete received, packets: %d", count);
/* verify that the result buffer is not getting overrun */
if (unlikely(count > TX_HW_RESULT_QUEUE_LEN))
@ -409,6 +398,19 @@ void wl1271_tx_complete(struct wl1271 *wl)
wl->tx_results_count++;
}
if (test_bit(WL1271_FLAG_TX_QUEUE_STOPPED, &wl->flags) &&
skb_queue_len(&wl->tx_queue) <= WL1271_TX_QUEUE_LOW_WATERMARK) {
unsigned long flags;
/* firmware buffer has space, restart queues */
wl1271_debug(DEBUG_TX, "tx_complete: waking queues");
spin_lock_irqsave(&wl->wl_lock, flags);
ieee80211_wake_queues(wl->hw);
clear_bit(WL1271_FLAG_TX_QUEUE_STOPPED, &wl->flags);
spin_unlock_irqrestore(&wl->wl_lock, flags);
ieee80211_queue_work(wl->hw, &wl->tx_work);
}
}
/* caller must hold wl->mutex */