rt2x00: Convert rt2500pci interrupt handling to use tasklets

Fix interrupt processing on slow machines by using individual tasklets
for each different device interrupt. This ensures that while a RX or TX
status tasklet is scheduled only the according device interrupt is
masked and other interrupts such as TBTT can still be processed.

Also, this allows us to use tasklet_hi_schedule for TBTT processing
which is required to not send out beacons with a wrong DTIM count (due
to delayed periodic beacon updates). Furthermore, this improves the
latency between the TBTT and sending out buffered multi- and broadcast
traffic.

As a nice bonus, the interrupt handling overhead should be much lower.

Compile-tested only.

Signed-off-by: Helmut Schaa <helmut.schaa@googlemail.com>
Acked-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --git a/drivers/net/wireless/rt2x00/rt2500pci.c b/drivers/net/wireless/rt2x00/rt2500pci.c
index 5225ae1899fe80cd4b722fbffec544e621ecc320..7daa483c374214ad1a12c461e25e31bd38313b45 100644 (file)
--- a/drivers/net/wireless/rt2x00/rt2500pci.c
+++ b/drivers/net/wireless/rt2x00/rt2500pci.c
@@ -735,6 +735,11 @@ static void rt2500pci_start_queue(struct data_queue *queue)
                rt2x00pci_register_write(rt2x00dev, RXCSR0, reg);
                break;
        case QID_BEACON:
+               /*
+                * Allow the tbtt tasklet to be scheduled.
+                */
+               tasklet_enable(&rt2x00dev->tbtt_tasklet);
+
                rt2x00pci_register_read(rt2x00dev, CSR14, &reg);
                rt2x00_set_field32(&reg, CSR14_TSF_COUNT, 1);
                rt2x00_set_field32(&reg, CSR14_TBCN, 1);
@@ -796,6 +801,11 @@ static void rt2500pci_stop_queue(struct data_queue *queue)
                rt2x00_set_field32(&reg, CSR14_TBCN, 0);
                rt2x00_set_field32(&reg, CSR14_BEACON_GEN, 0);
                rt2x00pci_register_write(rt2x00dev, CSR14, reg);
+
+               /*
+                * Wait for possibly running tbtt tasklets.
+                */
+               tasklet_disable(&rt2x00dev->tbtt_tasklet);
                break;
        default:
                break;
@@ -1119,6 +1129,7 @@ static void rt2500pci_toggle_irq(struct rt2x00_dev *rt2x00dev,
        int mask = (state == STATE_RADIO_IRQ_OFF) ||
                   (state == STATE_RADIO_IRQ_OFF_ISR);
        u32 reg;
+       unsigned long flags;
 
        /*
         * When interrupts are being enabled, the interrupt registers
@@ -1127,12 +1138,20 @@ static void rt2500pci_toggle_irq(struct rt2x00_dev *rt2x00dev,
        if (state == STATE_RADIO_IRQ_ON) {
                rt2x00pci_register_read(rt2x00dev, CSR7, &reg);
                rt2x00pci_register_write(rt2x00dev, CSR7, reg);
+
+               /*
+                * Enable tasklets.
+                */
+               tasklet_enable(&rt2x00dev->txstatus_tasklet);
+               tasklet_enable(&rt2x00dev->rxdone_tasklet);
        }
 
        /*
         * Only toggle the interrupts bits we are going to use.
         * Non-checked interrupt bits are disabled by default.
         */
+       spin_lock_irqsave(&rt2x00dev->irqmask_lock, flags);
+
        rt2x00pci_register_read(rt2x00dev, CSR8, &reg);
        rt2x00_set_field32(&reg, CSR8_TBCN_EXPIRE, mask);
        rt2x00_set_field32(&reg, CSR8_TXDONE_TXRING, mask);
@@ -1140,6 +1159,16 @@ static void rt2500pci_toggle_irq(struct rt2x00_dev *rt2x00dev,
        rt2x00_set_field32(&reg, CSR8_TXDONE_PRIORING, mask);
        rt2x00_set_field32(&reg, CSR8_RXDONE, mask);
        rt2x00pci_register_write(rt2x00dev, CSR8, reg);
+
+       spin_unlock_irqrestore(&rt2x00dev->irqmask_lock, flags);
+
+       if (state == STATE_RADIO_IRQ_OFF) {
+               /*
+                * Ensure that all tasklets are finished.
+                */
+               tasklet_disable(&rt2x00dev->txstatus_tasklet);
+               tasklet_disable(&rt2x00dev->rxdone_tasklet);
+       }
 }
 
 static int rt2500pci_enable_radio(struct rt2x00_dev *rt2x00dev)
@@ -1418,58 +1447,71 @@ static void rt2500pci_txdone(struct rt2x00_dev *rt2x00dev,
        }
 }
 
-static irqreturn_t rt2500pci_interrupt_thread(int irq, void *dev_instance)
+static void rt2500pci_enable_interrupt(struct rt2x00_dev *rt2x00dev,
+                                      struct rt2x00_field32 irq_field)
 {
-       struct rt2x00_dev *rt2x00dev = dev_instance;
-       u32 reg = rt2x00dev->irqvalue[0];
+       unsigned long flags;
+       u32 reg;
 
        /*
-        * Handle interrupts, walk through all bits
-        * and run the tasks, the bits are checked in order of
-        * priority.
+        * Enable a single interrupt. The interrupt mask register
+        * access needs locking.
         */
+       spin_lock_irqsave(&rt2x00dev->irqmask_lock, flags);
 
-       /*
-        * 1 - Beacon timer expired interrupt.
-        */
-       if (rt2x00_get_field32(reg, CSR7_TBCN_EXPIRE))
-               rt2x00lib_beacondone(rt2x00dev);
+       rt2x00pci_register_read(rt2x00dev, CSR8, &reg);
+       rt2x00_set_field32(&reg, irq_field, 0);
+       rt2x00pci_register_write(rt2x00dev, CSR8, reg);
 
-       /*
-        * 2 - Rx ring done interrupt.
-        */
-       if (rt2x00_get_field32(reg, CSR7_RXDONE))
-               rt2x00pci_rxdone(rt2x00dev);
+       spin_unlock_irqrestore(&rt2x00dev->irqmask_lock, flags);
+}
 
-       /*
-        * 3 - Atim ring transmit done interrupt.
-        */
-       if (rt2x00_get_field32(reg, CSR7_TXDONE_ATIMRING))
-               rt2500pci_txdone(rt2x00dev, QID_ATIM);
+static void rt2500pci_txstatus_tasklet(unsigned long data)
+{
+       struct rt2x00_dev *rt2x00dev = (struct rt2x00_dev *)data;
+       u32 reg;
+       unsigned long flags;
 
        /*
-        * 4 - Priority ring transmit done interrupt.
+        * Handle all tx queues.
         */
-       if (rt2x00_get_field32(reg, CSR7_TXDONE_PRIORING))
-               rt2500pci_txdone(rt2x00dev, QID_AC_VO);
+       rt2500pci_txdone(rt2x00dev, QID_ATIM);
+       rt2500pci_txdone(rt2x00dev, QID_AC_VO);
+       rt2500pci_txdone(rt2x00dev, QID_AC_VI);
 
        /*
-        * 5 - Tx ring transmit done interrupt.
+        * Enable all TXDONE interrupts again.
         */
-       if (rt2x00_get_field32(reg, CSR7_TXDONE_TXRING))
-               rt2500pci_txdone(rt2x00dev, QID_AC_VI);
+       spin_lock_irqsave(&rt2x00dev->irqmask_lock, flags);
 
-       /* Enable interrupts again. */
-       rt2x00dev->ops->lib->set_device_state(rt2x00dev,
-                                             STATE_RADIO_IRQ_ON_ISR);
+       rt2x00pci_register_read(rt2x00dev, CSR8, &reg);
+       rt2x00_set_field32(&reg, CSR8_TXDONE_TXRING, 0);
+       rt2x00_set_field32(&reg, CSR8_TXDONE_ATIMRING, 0);
+       rt2x00_set_field32(&reg, CSR8_TXDONE_PRIORING, 0);
+       rt2x00pci_register_write(rt2x00dev, CSR8, reg);
 
-       return IRQ_HANDLED;
+       spin_unlock_irqrestore(&rt2x00dev->irqmask_lock, flags);
+}
+
+static void rt2500pci_tbtt_tasklet(unsigned long data)
+{
+       struct rt2x00_dev *rt2x00dev = (struct rt2x00_dev *)data;
+       rt2x00lib_beacondone(rt2x00dev);
+       rt2500pci_enable_interrupt(rt2x00dev, CSR8_TBCN_EXPIRE);
+}
+
+static void rt2500pci_rxdone_tasklet(unsigned long data)
+{
+       struct rt2x00_dev *rt2x00dev = (struct rt2x00_dev *)data;
+       rt2x00pci_rxdone(rt2x00dev);
+       rt2500pci_enable_interrupt(rt2x00dev, CSR8_RXDONE);
 }
 
 static irqreturn_t rt2500pci_interrupt(int irq, void *dev_instance)
 {
        struct rt2x00_dev *rt2x00dev = dev_instance;
-       u32 reg;
+       u32 reg, mask;
+       unsigned long flags;
 
        /*
         * Get the interrupt sources & saved to local variable.
@@ -1484,14 +1526,42 @@ static irqreturn_t rt2500pci_interrupt(int irq, void *dev_instance)
        if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
                return IRQ_HANDLED;
 
-       /* Store irqvalues for use in the interrupt thread. */
-       rt2x00dev->irqvalue[0] = reg;
+       mask = reg;
+
+       /*
+        * Schedule tasklets for interrupt handling.
+        */
+       if (rt2x00_get_field32(reg, CSR7_TBCN_EXPIRE))
+               tasklet_hi_schedule(&rt2x00dev->tbtt_tasklet);
+
+       if (rt2x00_get_field32(reg, CSR7_RXDONE))
+               tasklet_schedule(&rt2x00dev->rxdone_tasklet);
+
+       if (rt2x00_get_field32(reg, CSR7_TXDONE_ATIMRING) ||
+           rt2x00_get_field32(reg, CSR7_TXDONE_PRIORING) ||
+           rt2x00_get_field32(reg, CSR7_TXDONE_TXRING)) {
+               tasklet_schedule(&rt2x00dev->txstatus_tasklet);
+               /*
+                * Mask out all txdone interrupts.
+                */
+               rt2x00_set_field32(&mask, CSR8_TXDONE_TXRING, 1);
+               rt2x00_set_field32(&mask, CSR8_TXDONE_ATIMRING, 1);
+               rt2x00_set_field32(&mask, CSR8_TXDONE_PRIORING, 1);
+       }
+
+       /*
+        * Disable all interrupts for which a tasklet was scheduled right now,
+        * the tasklet will reenable the appropriate interrupts.
+        */
+       spin_lock_irqsave(&rt2x00dev->irqmask_lock, flags);
 
-       /* Disable interrupts, will be enabled again in the interrupt thread. */
-       rt2x00dev->ops->lib->set_device_state(rt2x00dev,
-                                             STATE_RADIO_IRQ_OFF_ISR);
+       rt2x00pci_register_read(rt2x00dev, CSR8, &reg);
+       reg |= mask;
+       rt2x00pci_register_write(rt2x00dev, CSR8, reg);
+
+       spin_unlock_irqrestore(&rt2x00dev->irqmask_lock, flags);
 
-       return IRQ_WAKE_THREAD;
+       return IRQ_HANDLED;
 }
 
 /*
@@ -1948,7 +2018,9 @@ static const struct ieee80211_ops rt2500pci_mac80211_ops = {
 
 static const struct rt2x00lib_ops rt2500pci_rt2x00_ops = {
        .irq_handler            = rt2500pci_interrupt,
-       .irq_handler_thread     = rt2500pci_interrupt_thread,
+       .txstatus_tasklet       = rt2500pci_txstatus_tasklet,
+       .tbtt_tasklet           = rt2500pci_tbtt_tasklet,
+       .rxdone_tasklet         = rt2500pci_rxdone_tasklet,
        .probe_hw               = rt2500pci_probe_hw,
        .initialize             = rt2x00pci_initialize,
        .uninitialize           = rt2x00pci_uninitialize,