[rt2x00-users] [PATCH 07/12] rt2x00: Convert rt2800pci to use tasklets

Gertjan van Wingerde gwingerde at gmail.com
Sat Jan 15 08:58:05 EST 2011


On 01/14/11 10:41, Helmut Schaa wrote:
> 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 and PRETBTT
> 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 is reduced such that
> rt2800pci gains around 25% more throuhput on a rt3052 MIPS board.
> 
> Signed-off-by: Helmut Schaa <helmut.schaa at googlemail.com>

Acked-by: Gertjan van Wingerde <gwingerde at gmail.com>

> ---
>  drivers/net/wireless/rt2x00/rt2800pci.c |  173 ++++++++++++++++++++-----------
>  1 files changed, 114 insertions(+), 59 deletions(-)
> 
> diff --git a/drivers/net/wireless/rt2x00/rt2800pci.c b/drivers/net/wireless/rt2x00/rt2800pci.c
> index e4d97ad..3eaa4fd 100644
> --- a/drivers/net/wireless/rt2x00/rt2800pci.c
> +++ b/drivers/net/wireless/rt2x00/rt2800pci.c
> @@ -200,6 +200,13 @@ static void rt2800pci_start_queue(struct data_queue *queue)
>  		rt2800_register_write(rt2x00dev, MAC_SYS_CTRL, reg);
>  		break;
>  	case QID_BEACON:
> +		/*
> +		 * Allow beacon tasklets to be scheduled for periodic
> +		 * beacon updates.
> +		 */
> +		tasklet_enable(&rt2x00dev->tbtt_tasklet);
> +		tasklet_enable(&rt2x00dev->pretbtt_tasklet);
> +
>  		rt2800_register_read(rt2x00dev, BCN_TIME_CFG, &reg);
>  		rt2x00_set_field32(&reg, BCN_TIME_CFG_TSF_TICKING, 1);
>  		rt2x00_set_field32(&reg, BCN_TIME_CFG_TBTT_ENABLE, 1);
> @@ -258,6 +265,12 @@ static void rt2800pci_stop_queue(struct data_queue *queue)
>  		rt2800_register_read(rt2x00dev, INT_TIMER_EN, &reg);
>  		rt2x00_set_field32(&reg, INT_TIMER_EN_PRE_TBTT_TIMER, 0);
>  		rt2800_register_write(rt2x00dev, INT_TIMER_EN, reg);
> +
> +		/*
> +		 * Wait for tbtt tasklets to finish.
> +		 */
> +		tasklet_disable(&rt2x00dev->tbtt_tasklet);
> +		tasklet_disable(&rt2x00dev->pretbtt_tasklet);
>  		break;
>  	default:
>  		break;
> @@ -408,6 +421,7 @@ static void rt2800pci_toggle_irq(struct rt2x00_dev *rt2x00dev,
>  	int mask = (state == STATE_RADIO_IRQ_ON) ||
>  		   (state == STATE_RADIO_IRQ_ON_ISR);
>  	u32 reg;
> +	unsigned long flags;
>  
>  	/*
>  	 * When interrupts are being enabled, the interrupt registers
> @@ -417,10 +431,16 @@ static void rt2800pci_toggle_irq(struct rt2x00_dev *rt2x00dev,
>  		rt2800_register_read(rt2x00dev, INT_SOURCE_CSR, &reg);
>  		rt2800_register_write(rt2x00dev, INT_SOURCE_CSR, reg);
>  
> +		/*
> +		 * Enable tasklets. The beacon related tasklets are
> +		 * enabled when the beacon queue is started.
> +		 */
>  		tasklet_enable(&rt2x00dev->txstatus_tasklet);
> -	} else if (state == STATE_RADIO_IRQ_OFF)
> -		tasklet_disable(&rt2x00dev->txstatus_tasklet);
> +		tasklet_enable(&rt2x00dev->rxdone_tasklet);
> +		tasklet_enable(&rt2x00dev->autowake_tasklet);
> +	} 
>  
> +	spin_lock_irqsave(&rt2x00dev->irqmask_lock, flags);
>  	rt2800_register_read(rt2x00dev, INT_MASK_CSR, &reg);
>  	rt2x00_set_field32(&reg, INT_MASK_CSR_RXDELAYINT, 0);
>  	rt2x00_set_field32(&reg, INT_MASK_CSR_TXDELAYINT, 0);
> @@ -441,6 +461,17 @@ static void rt2800pci_toggle_irq(struct rt2x00_dev *rt2x00dev,
>  	rt2x00_set_field32(&reg, INT_MASK_CSR_RX_COHERENT, 0);
>  	rt2x00_set_field32(&reg, INT_MASK_CSR_TX_COHERENT, 0);
>  	rt2800_register_write(rt2x00dev, INT_MASK_CSR, 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);
> +		tasklet_disable(&rt2x00dev->autowake_tasklet);
> +	}
>  }
>  
>  static int rt2800pci_init_registers(struct rt2x00_dev *rt2x00dev)
> @@ -721,45 +752,60 @@ static void rt2800pci_txdone(struct rt2x00_dev *rt2x00dev)
>  	}
>  }
>  
> -static void rt2800pci_txstatus_tasklet(unsigned long data)
> -{
> -	rt2800pci_txdone((struct rt2x00_dev *)data);
> -}
> -
> -static irqreturn_t rt2800pci_interrupt_thread(int irq, void *dev_instance)
> +static void rt2800pci_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;
>  
>  	/*
> -	 * 1 - Pre TBTT interrupt.
> +	 * Enable a single interrupt. The interrupt mask register
> +	 * access needs locking.
>  	 */
> -	if (rt2x00_get_field32(reg, INT_SOURCE_CSR_PRE_TBTT))
> -		rt2x00lib_pretbtt(rt2x00dev);
> +	spin_lock_irqsave(&rt2x00dev->irqmask_lock, flags);
> +	rt2800_register_read(rt2x00dev, INT_MASK_CSR, &reg);
> +	rt2x00_set_field32(&reg, irq_field, 1);
> +	rt2800_register_write(rt2x00dev, INT_MASK_CSR, reg);
> +	spin_unlock_irqrestore(&rt2x00dev->irqmask_lock, flags);
> +}
>  
> -	/*
> -	 * 2 - Beacondone interrupt.
> -	 */
> -	if (rt2x00_get_field32(reg, INT_SOURCE_CSR_TBTT))
> -		rt2x00lib_beacondone(rt2x00dev);
> +static void rt2800pci_txstatus_tasklet(unsigned long data)
> +{
> +	rt2800pci_txdone((struct rt2x00_dev *)data);
>  
>  	/*
> -	 * 3 - Rx ring done interrupt.
> +	 * No need to enable the tx status interrupt here as we always
> +	 * leave it enabled to minimize the possibility of a tx status
> +	 * register overflow. See comment in interrupt handler.
>  	 */
> -	if (rt2x00_get_field32(reg, INT_SOURCE_CSR_RX_DONE))
> -		rt2x00pci_rxdone(rt2x00dev);
> +}
>  
> -	/*
> -	 * 4 - Auto wakeup interrupt.
> -	 */
> -	if (rt2x00_get_field32(reg, INT_SOURCE_CSR_AUTO_WAKEUP))
> -		rt2800pci_wakeup(rt2x00dev);
> +static void rt2800pci_pretbtt_tasklet(unsigned long data)
> +{
> +	struct rt2x00_dev *rt2x00dev = (struct rt2x00_dev *)data;
> +	rt2x00lib_pretbtt(rt2x00dev);
> +	rt2800pci_enable_interrupt(rt2x00dev, INT_MASK_CSR_PRE_TBTT);
> +}
>  
> -	/* Enable interrupts again. */
> -	rt2x00dev->ops->lib->set_device_state(rt2x00dev,
> -					      STATE_RADIO_IRQ_ON_ISR);
> +static void rt2800pci_tbtt_tasklet(unsigned long data)
> +{
> +	struct rt2x00_dev *rt2x00dev = (struct rt2x00_dev *)data;
> +	rt2x00lib_beacondone(rt2x00dev);
> +	rt2800pci_enable_interrupt(rt2x00dev, INT_MASK_CSR_TBTT);
> +}
>  
> -	return IRQ_HANDLED;
> +static void rt2800pci_rxdone_tasklet(unsigned long data)
> +{
> +	struct rt2x00_dev *rt2x00dev = (struct rt2x00_dev *)data;
> +	rt2x00pci_rxdone(rt2x00dev);
> +	rt2800pci_enable_interrupt(rt2x00dev, INT_MASK_CSR_RX_DONE);
> +}
> +
> +static void rt2800pci_autowake_tasklet(unsigned long data)
> +{
> +	struct rt2x00_dev *rt2x00dev = (struct rt2x00_dev *)data;
> +	rt2800pci_wakeup(rt2x00dev);
> +	rt2800pci_enable_interrupt(rt2x00dev, INT_MASK_CSR_AUTO_WAKEUP);
>  }
>  
>  static void rt2800pci_txstatus_interrupt(struct rt2x00_dev *rt2x00dev)
> @@ -805,8 +851,8 @@ static void rt2800pci_txstatus_interrupt(struct rt2x00_dev *rt2x00dev)
>  static irqreturn_t rt2800pci_interrupt(int irq, void *dev_instance)
>  {
>  	struct rt2x00_dev *rt2x00dev = dev_instance;
> -	u32 reg;
> -	irqreturn_t ret = IRQ_HANDLED;
> +	u32 reg, mask;
> +	unsigned long flags;
>  
>  	/* Read status and ACK all interrupts */
>  	rt2800_register_read(rt2x00dev, INT_SOURCE_CSR, &reg);
> @@ -818,38 +864,44 @@ static irqreturn_t rt2800pci_interrupt(int irq, void *dev_instance)
>  	if (!test_bit(DEVICE_STATE_ENABLED_RADIO, &rt2x00dev->flags))
>  		return IRQ_HANDLED;
>  
> -	if (rt2x00_get_field32(reg, INT_SOURCE_CSR_TX_FIFO_STATUS))
> -		rt2800pci_txstatus_interrupt(rt2x00dev);
> +	/*
> +	 * Since INT_MASK_CSR and INT_SOURCE_CSR use the same bits
> +	 * for interrupts and interrupt masks we can just use the value of
> +	 * INT_SOURCE_CSR to create the interrupt mask.
> +	 */
> +	mask = ~reg;
>  
> -	if (rt2x00_get_field32(reg, INT_SOURCE_CSR_PRE_TBTT) ||
> -	    rt2x00_get_field32(reg, INT_SOURCE_CSR_TBTT) ||
> -	    rt2x00_get_field32(reg, INT_SOURCE_CSR_RX_DONE) ||
> -	    rt2x00_get_field32(reg, INT_SOURCE_CSR_AUTO_WAKEUP)) {
> +	if (rt2x00_get_field32(reg, INT_SOURCE_CSR_TX_FIFO_STATUS)) {
> +		rt2800pci_txstatus_interrupt(rt2x00dev);
>  		/*
> -		 * All other interrupts are handled in the interrupt thread.
> -		 * Store irqvalue for use in the interrupt thread.
> +		 * Never disable the TX_FIFO_STATUS interrupt.
>  		 */
> -		rt2x00dev->irqvalue[0] = reg;
> +		rt2x00_set_field32(&mask, INT_MASK_CSR_TX_FIFO_STATUS, 1);
> +	}
>  
> -		/*
> -		 * Disable interrupts, will be enabled again in the
> -		 * interrupt thread.
> -		*/
> -		rt2x00dev->ops->lib->set_device_state(rt2x00dev,
> -						      STATE_RADIO_IRQ_OFF_ISR);
> +	if (rt2x00_get_field32(reg, INT_SOURCE_CSR_PRE_TBTT))
> +		tasklet_hi_schedule(&rt2x00dev->pretbtt_tasklet);
>  
> -		/*
> -		 * Leave the TX_FIFO_STATUS interrupt enabled to not lose any
> -		 * tx status reports.
> -		 */
> -		rt2800_register_read(rt2x00dev, INT_MASK_CSR, &reg);
> -		rt2x00_set_field32(&reg, INT_MASK_CSR_TX_FIFO_STATUS, 1);
> -		rt2800_register_write(rt2x00dev, INT_MASK_CSR, reg);
> +	if (rt2x00_get_field32(reg, INT_SOURCE_CSR_TBTT))
> +		tasklet_hi_schedule(&rt2x00dev->tbtt_tasklet);
>  
> -		ret = IRQ_WAKE_THREAD;
> -	}
> +	if (rt2x00_get_field32(reg, INT_SOURCE_CSR_RX_DONE))
> +		tasklet_schedule(&rt2x00dev->rxdone_tasklet);
>  
> -	return ret;
> +	if (rt2x00_get_field32(reg, INT_SOURCE_CSR_AUTO_WAKEUP))
> +		tasklet_schedule(&rt2x00dev->autowake_tasklet);
> +
> +	/*
> +	 * 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);
> +	rt2800_register_read(rt2x00dev, INT_MASK_CSR, &reg);
> +	reg &= mask;
> +	rt2800_register_write(rt2x00dev, INT_MASK_CSR, reg);
> +	spin_unlock_irqrestore(&rt2x00dev->irqmask_lock, flags);
> +
> +	return IRQ_HANDLED;
>  }
>  
>  /*
> @@ -964,8 +1016,11 @@ static const struct rt2800_ops rt2800pci_rt2800_ops = {
>  
>  static const struct rt2x00lib_ops rt2800pci_rt2x00_ops = {
>  	.irq_handler		= rt2800pci_interrupt,
> -	.irq_handler_thread	= rt2800pci_interrupt_thread,
> -	.txstatus_tasklet       = rt2800pci_txstatus_tasklet,
> +	.txstatus_tasklet	= rt2800pci_txstatus_tasklet,
> +	.pretbtt_tasklet	= rt2800pci_pretbtt_tasklet,
> +	.tbtt_tasklet		= rt2800pci_tbtt_tasklet,
> +	.rxdone_tasklet		= rt2800pci_rxdone_tasklet,
> +	.autowake_tasklet	= rt2800pci_autowake_tasklet,
>  	.probe_hw		= rt2800pci_probe_hw,
>  	.get_firmware_name	= rt2800pci_get_firmware_name,
>  	.check_firmware		= rt2800_check_firmware,




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