From 06f7bc7db79fabe6b2ec16eff0f59e4acc21eb72 Mon Sep 17 00:00:00 2001 From: Juuso Oikarinen Date: Mon, 22 Feb 2010 08:38:33 +0200 Subject: [PATCH] wl1271: Fix queue stopping/waking for TX path 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 Reviewed-by: Kalle Valo Signed-off-by: John W. Linville --- drivers/net/wireless/wl12xx/wl1271.h | 3 ++- drivers/net/wireless/wl12xx/wl1271_main.c | 12 +++++------- drivers/net/wireless/wl12xx/wl1271_tx.c | 28 +++++++++++++++------------- 3 files changed, 22 insertions(+), 21 deletions(-) diff --git a/drivers/net/wireless/wl12xx/wl1271.h b/drivers/net/wireless/wl12xx/wl1271.h index cc974ea..7f03f89 100644 --- a/drivers/net/wireless/wl12xx/wl1271.h +++ b/drivers/net/wireless/wl12xx/wl1271.h @@ -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 */ diff --git a/drivers/net/wireless/wl12xx/wl1271_main.c b/drivers/net/wireless/wl12xx/wl1271_main.c index 81fb02e..184264a 100644 --- a/drivers/net/wireless/wl12xx/wl1271_main.c +++ b/drivers/net/wireless/wl12xx/wl1271_main.c @@ -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; diff --git a/drivers/net/wireless/wl12xx/wl1271_tx.c b/drivers/net/wireless/wl12xx/wl1271_tx.c index 2e057b0..7926471 100644 --- a/drivers/net/wireless/wl12xx/wl1271_tx.c +++ b/drivers/net/wireless/wl12xx/wl1271_tx.c @@ -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 */ -- 2.7.4