wl12xx: Switch to a threaded interrupt handler

To achieve maximal throughput, it is very important to react to
interrupts as soon as possible. Currently the interrupt handler wakes up
a worker for handling interrupts in process context. A cleaner and more
efficient design would be to request a threaded interrupt handler.  This
handler's priority is very high, and can do blocking operations such as
SDIO/SPI transactions.

Some work can be deferred, mostly calls to mac80211 APIs
(ieee80211_rx_ni and ieee80211_tx_status). By deferring such work to a
different worker, we can keep the irq handler thread more I/O
responsive. In addition, on multi-core systems the two threads can be
scheduled on different cores, which will improve overall performance.

The use of WL1271_FLAG_IRQ_PENDING & WL1271_FLAG_IRQ_RUNNING was
changed. For simplicity, always query the FW for more pending
interrupts. Since there are relatively long bursts of interrupts, the
extra FW status read overhead is negligible. In addition, this enables
registering the IRQ handler with the ONESHOT option.

Signed-off-by: Ido Yariv <ido@wizery.com>
Reviewed-by: Luciano Coelho <coelho@ti.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>

1 files changed, 7 insertions, 12 deletions

diff --git a/drivers/net/wireless/wl12xx/spi.c b/drivers/net/wireless/wl12xx/spi.c
index 0132dad..df5a00f1 100644
--- a/drivers/net/wireless/wl12xx/spi.c
+++ b/drivers/net/wireless/wl12xx/spi.c
@@ -320,28 +320,23 @@ static void wl1271_spi_raw_write(struct wl1271 *wl, int addr, void *buf,
 	spi_sync(wl_to_spi(wl), &m);
 }
 
-static irqreturn_t wl1271_irq(int irq, void *cookie)
+static irqreturn_t wl1271_hardirq(int irq, void *cookie)
 {
-	struct wl1271 *wl;
+	struct wl1271 *wl = cookie;
 	unsigned long flags;
 
 	wl1271_debug(DEBUG_IRQ, "IRQ");
 
-	wl = cookie;
-
 	/* complete the ELP completion */
 	spin_lock_irqsave(&wl->wl_lock, flags);
+	set_bit(WL1271_FLAG_IRQ_RUNNING, &wl->flags);
 	if (wl->elp_compl) {
 		complete(wl->elp_compl);
 		wl->elp_compl = NULL;
 	}
-
-	if (!test_and_set_bit(WL1271_FLAG_IRQ_RUNNING, &wl->flags))
-		ieee80211_queue_work(wl->hw, &wl->irq_work);
-	set_bit(WL1271_FLAG_IRQ_PENDING, &wl->flags);
 	spin_unlock_irqrestore(&wl->wl_lock, flags);
 
-	return IRQ_HANDLED;
+	return IRQ_WAKE_THREAD;
 }
 
 static int wl1271_spi_set_power(struct wl1271 *wl, bool enable)
@@ -413,14 +408,14 @@ static int __devinit wl1271_probe(struct spi_device *spi)
 		goto out_free;
 	}
 
-	ret = request_irq(wl->irq, wl1271_irq, 0, DRIVER_NAME, wl);
+	ret = request_threaded_irq(wl->irq, wl1271_hardirq, wl1271_irq,
+				   IRQF_TRIGGER_RISING,
+				   DRIVER_NAME, wl);
 	if (ret < 0) {
 		wl1271_error("request_irq() failed: %d", ret);
 		goto out_free;
 	}
 
-	set_irq_type(wl->irq, IRQ_TYPE_EDGE_RISING);
-
 	disable_irq(wl->irq);
 
 	ret = wl1271_init_ieee80211(wl);