[RFC/RFT 1/8] rt2800: partially restore old mmio txstatus behaviour

[Stanislaw Gruszka <sgruszka@xxxxxxxxxx>]

Do not disable txstatus interrupt and add quota of processed tx statuses in
one tasklet. Quota is needed to allow to fed device with new frames during
processing of tx statuses.

Patch fixes about 15% performance degradation on some scenarios coused by
0b0d556e0ebb ("rt2800mmio: use txdone/txstatus routines from lib").

Signed-off-by: Stanislaw Gruszka <sgruszka@xxxxxxxxxx>
---
 drivers/net/wireless/ralink/rt2x00/rt2800lib.c  |  4 ++--
 drivers/net/wireless/ralink/rt2x00/rt2800lib.h  |  2 +-
 drivers/net/wireless/ralink/rt2x00/rt2800mmio.c | 30 +++++++------------------
 drivers/net/wireless/ralink/rt2x00/rt2800usb.c  |  2 +-
 4 files changed, 12 insertions(+), 26 deletions(-)

diff --git a/drivers/net/wireless/ralink/rt2x00/rt2800lib.c b/drivers/net/wireless/ralink/rt2x00/rt2800lib.c
index 0e95555aec62..fdf7813d9be6 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2800lib.c
+++ b/drivers/net/wireless/ralink/rt2x00/rt2800lib.c
@@ -1100,7 +1100,7 @@ void rt2800_txdone_entry(struct queue_entry *entry, u32 status, __le32 *txwi,
 }
 EXPORT_SYMBOL_GPL(rt2800_txdone_entry);
 
-void rt2800_txdone(struct rt2x00_dev *rt2x00dev)
+void rt2800_txdone(struct rt2x00_dev *rt2x00dev, unsigned int quota)
 {
 	struct data_queue *queue;
 	struct queue_entry *entry;
@@ -1108,7 +1108,7 @@ void rt2800_txdone(struct rt2x00_dev *rt2x00dev)
 	u8 qid;
 	bool match;
 
-	while (kfifo_get(&rt2x00dev->txstatus_fifo, &reg)) {
+	while (quota-- > 0 && kfifo_get(&rt2x00dev->txstatus_fifo, &reg)) {
 		/*
 		 * TX_STA_FIFO_PID_QUEUE is a 2-bit field, thus qid is
 		 * guaranteed to be one of the TX QIDs .
diff --git a/drivers/net/wireless/ralink/rt2x00/rt2800lib.h b/drivers/net/wireless/ralink/rt2x00/rt2800lib.h
index 0dff2c7b3010..506c319070dd 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2800lib.h
+++ b/drivers/net/wireless/ralink/rt2x00/rt2800lib.h
@@ -195,7 +195,7 @@ void rt2800_process_rxwi(struct queue_entry *entry, struct rxdone_entry_desc *tx
 
 void rt2800_txdone_entry(struct queue_entry *entry, u32 status, __le32 *txwi,
 			 bool match);
-void rt2800_txdone(struct rt2x00_dev *rt2x00dev);
+void rt2800_txdone(struct rt2x00_dev *rt2x00dev, unsigned int quota);
 void rt2800_txdone_nostatus(struct rt2x00_dev *rt2x00dev);
 bool rt2800_txstatus_timeout(struct rt2x00_dev *rt2x00dev);
 
diff --git a/drivers/net/wireless/ralink/rt2x00/rt2800mmio.c b/drivers/net/wireless/ralink/rt2x00/rt2800mmio.c
index ddb88cfeace2..f7635a47dbcd 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2800mmio.c
+++ b/drivers/net/wireless/ralink/rt2x00/rt2800mmio.c
@@ -255,20 +255,6 @@ void rt2800mmio_autowake_tasklet(unsigned long data)
 }
 EXPORT_SYMBOL_GPL(rt2800mmio_autowake_tasklet);
 
-static void rt2800mmio_txdone(struct rt2x00_dev *rt2x00dev)
-{
-	bool timeout = false;
-
-	while (!kfifo_is_empty(&rt2x00dev->txstatus_fifo) ||
-	       (timeout = rt2800_txstatus_timeout(rt2x00dev))) {
-
-		rt2800_txdone(rt2x00dev);
-
-		if (timeout)
-			rt2800_txdone_nostatus(rt2x00dev);
-	}
-}
-
 static bool rt2800mmio_fetch_txstatus(struct rt2x00_dev *rt2x00dev)
 {
 	u32 status;
@@ -305,14 +291,11 @@ void rt2800mmio_txstatus_tasklet(unsigned long data)
 {
 	struct rt2x00_dev *rt2x00dev = (struct rt2x00_dev *)data;
 
-	do {
-		rt2800mmio_txdone(rt2x00dev);
+	rt2800_txdone(rt2x00dev, 16);
 
-	} while (rt2800mmio_fetch_txstatus(rt2x00dev));
+	if (!kfifo_is_empty(&rt2x00dev->txstatus_fifo))
+		tasklet_schedule(&rt2x00dev->txstatus_tasklet);
 
-	if (test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
-		rt2800mmio_enable_interrupt(rt2x00dev,
-					    INT_SOURCE_CSR_TX_FIFO_STATUS);
 }
 EXPORT_SYMBOL_GPL(rt2800mmio_txstatus_tasklet);
 
@@ -339,8 +322,10 @@ irqreturn_t rt2800mmio_interrupt(int irq, void *dev_instance)
 	mask = ~reg;
 
 	if (rt2x00_get_field32(reg, INT_SOURCE_CSR_TX_FIFO_STATUS)) {
+		rt2x00_set_field32(&mask, INT_MASK_CSR_TX_FIFO_STATUS, 1);
 		rt2800mmio_fetch_txstatus(rt2x00dev);
-		tasklet_schedule(&rt2x00dev->txstatus_tasklet);
+		if (!kfifo_is_empty(&rt2x00dev->txstatus_fifo))
+			tasklet_schedule(&rt2x00dev->txstatus_tasklet);
 	}
 
 	if (rt2x00_get_field32(reg, INT_SOURCE_CSR_PRE_TBTT))
@@ -500,7 +485,8 @@ void rt2800mmio_flush_queue(struct data_queue *queue, bool drop)
 		 */
 		if (tx_queue) {
 			tasklet_disable(&rt2x00dev->txstatus_tasklet);
-			rt2800mmio_txdone(rt2x00dev);
+			rt2800_txdone(rt2x00dev, UINT_MAX);
+			rt2800_txdone_nostatus(rt2x00dev);
 			tasklet_enable(&rt2x00dev->txstatus_tasklet);
 		}
 
diff --git a/drivers/net/wireless/ralink/rt2x00/rt2800usb.c b/drivers/net/wireless/ralink/rt2x00/rt2800usb.c
index 19eabf16147b..0bdcab374203 100644
--- a/drivers/net/wireless/ralink/rt2x00/rt2800usb.c
+++ b/drivers/net/wireless/ralink/rt2x00/rt2800usb.c
@@ -480,7 +480,7 @@ static void rt2800usb_work_txdone(struct work_struct *work)
 	while (!kfifo_is_empty(&rt2x00dev->txstatus_fifo) ||
 	       rt2800_txstatus_timeout(rt2x00dev)) {
 
-		rt2800_txdone(rt2x00dev);
+		rt2800_txdone(rt2x00dev, UINT_MAX);
 
 		rt2800_txdone_nostatus(rt2x00dev);
 
-- 
2.7.5