Re: [Linux-zigbee-devel] [PATCH 2/2] mrf24j40: Keep the interrupt line enabled

I have seen the interrupt line going low forever with heavy traffic.

The at86rf230 driver has two isr, one for edge-triggered and another
for level-triggered interrupt. The latter uses
disable_irq_nosync/enable_irq which makes sense for level-triggered
interrupt. Otherwise the interrupt would be triggered again and again
until the scheduled work read the status register.

However I don't see the use of disable_irq/enable_irq with an
edge-triggered interrupt. Perhaps I'm missing something. Though I
don't see any harm using it anyway. As you said the interrupt should
be delayed until enable_irq() is called. In particular when
CONFIG_HARDIRQS_SW_RESEND is set.

David

2013/5/14 Alan Ott [off-list ref]:

On 5/9/13 11:19 AM, David Hauweele wrote:

quoted

Disabling the interrupt line could miss an IRQ and leave the line into a
low state hence locking the driver.

Have you observed this? My understanding is that the interrupt won't be lost
but instead delayed until enable_irq() is called.

I got this pattern from the other 802.15.4 drivers. Perhaps my understanding
is wrong.

quoted

Signed-off-by: David Hauweele <redacted>
---
  drivers/net/ieee802154/mrf24j40.c |    7 +------
  1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/drivers/net/ieee802154/mrf24j40.c

b/drivers/net/ieee802154/mrf24j40.c
index 1e3ddf3..6ef32f7 100644

--- a/drivers/net/ieee802154/mrf24j40.c
+++ b/drivers/net/ieee802154/mrf24j40.c

@@ -603,8 +603,6 @@ static irqreturn_t mrf24j40_isr(int irq, void *data)
  {
        struct mrf24j40 *devrec = data;

-       disable_irq_nosync(irq);
-
        schedule_work(&devrec->irqwork);

        return IRQ_HANDLED;

@@ -619,7 +617,7 @@ static void mrf24j40_isrwork(struct work_struct *work)
        /* Read the interrupt status */
        ret = read_short_reg(devrec, REG_INTSTAT, &intstat);
        if (ret)
-               goto out;
+               return;

        /* Check for TX complete */
        if (intstat & 0x1)

@@ -628,9 +626,6 @@ static void mrf24j40_isrwork(struct work_struct *work)
        /* Check for Rx */
        if (intstat & 0x8)
                schedule_work(&devrec->rxwork);
-
-out:
-       enable_irq(devrec->spi->irq);
  }

  static void mrf24j40_rxwork(struct work_struct *work)