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rt2x00: Convert rt2400pci interrupt handling to use tasklets
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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>
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Helmut Schaa authored and John W. Linville committed Jan 31, 2011
1 parent 16222a0 commit bcf3cfd
Showing 1 changed file with 115 additions and 39 deletions.
154 changes: 115 additions & 39 deletions drivers/net/wireless/rt2x00/rt2400pci.c
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Original file line number Diff line number Diff line change
Expand Up @@ -645,6 +645,11 @@ static void rt2400pci_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);
Expand Down Expand Up @@ -706,6 +711,11 @@ static void rt2400pci_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;
Expand Down Expand Up @@ -964,6 +974,7 @@ static void rt2400pci_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
Expand All @@ -972,19 +983,38 @@ static void rt2400pci_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);
rt2x00_set_field32(&reg, CSR8_TXDONE_ATIMRING, mask);
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 before
* disabling the interrupts.
*/
tasklet_disable(&rt2x00dev->txstatus_tasklet);
tasklet_disable(&rt2x00dev->rxdone_tasklet);
}
}

static int rt2400pci_enable_radio(struct rt2x00_dev *rt2x00dev)
Expand Down Expand Up @@ -1285,57 +1315,71 @@ static void rt2400pci_txdone(struct rt2x00_dev *rt2x00dev,
}
}

static irqreturn_t rt2400pci_interrupt_thread(int irq, void *dev_instance)
static void rt2400pci_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))
rt2400pci_txdone(rt2x00dev, QID_ATIM);
static void rt2400pci_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))
rt2400pci_txdone(rt2x00dev, QID_AC_VO);
rt2400pci_txdone(rt2x00dev, QID_ATIM);
rt2400pci_txdone(rt2x00dev, QID_AC_VO);
rt2400pci_txdone(rt2x00dev, QID_AC_VI);

/*
* 5 - Tx ring transmit done interrupt.
* Enable all TXDONE interrupts again.
*/
if (rt2x00_get_field32(reg, CSR7_TXDONE_TXRING))
rt2400pci_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);
return IRQ_HANDLED;
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);

spin_unlock_irqrestore(&rt2x00dev->irqmask_lock, flags);
}

static void rt2400pci_tbtt_tasklet(unsigned long data)
{
struct rt2x00_dev *rt2x00dev = (struct rt2x00_dev *)data;
rt2x00lib_beacondone(rt2x00dev);
rt2400pci_enable_interrupt(rt2x00dev, CSR8_TBCN_EXPIRE);
}

static void rt2400pci_rxdone_tasklet(unsigned long data)
{
struct rt2x00_dev *rt2x00dev = (struct rt2x00_dev *)data;
rt2x00pci_rxdone(rt2x00dev);
rt2400pci_enable_interrupt(rt2x00dev, CSR8_RXDONE);
}

static irqreturn_t rt2400pci_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.
Expand All @@ -1350,14 +1394,44 @@ static irqreturn_t rt2400pci_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 interrupts, will be enabled again in the interrupt thread. */
rt2x00dev->ops->lib->set_device_state(rt2x00dev,
STATE_RADIO_IRQ_OFF_ISR);
/*
* 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);

return IRQ_WAKE_THREAD;
rt2x00pci_register_read(rt2x00dev, CSR8, &reg);
reg |= mask;
rt2x00pci_register_write(rt2x00dev, CSR8, reg);

spin_unlock_irqrestore(&rt2x00dev->irqmask_lock, flags);



return IRQ_HANDLED;
}

/*
Expand Down Expand Up @@ -1651,7 +1725,9 @@ static const struct ieee80211_ops rt2400pci_mac80211_ops = {

static const struct rt2x00lib_ops rt2400pci_rt2x00_ops = {
.irq_handler = rt2400pci_interrupt,
.irq_handler_thread = rt2400pci_interrupt_thread,
.txstatus_tasklet = rt2400pci_txstatus_tasklet,
.tbtt_tasklet = rt2400pci_tbtt_tasklet,
.rxdone_tasklet = rt2400pci_rxdone_tasklet,
.probe_hw = rt2400pci_probe_hw,
.initialize = rt2x00pci_initialize,
.uninitialize = rt2x00pci_uninitialize,
Expand Down

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