From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hauweele Subject: Re: [Linux-zigbee-devel] [PATCH 2/2] mrf24j40: Keep the interrupt line enabled Date: Thu, 16 May 2013 23:34:11 +0200 Message-ID: References: <1368112788-25701-1-git-send-email-david@hauweele.net> <1368112788-25701-2-git-send-email-david@hauweele.net> <5191B5C4.2020609@signal11.us> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: Alexander Smirnov , Dmitry Eremin-Solenikov , linux-zigbee-devel@lists.sourceforge.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Alan Ott Return-path: In-Reply-To: <5191B5C4.2020609@signal11.us> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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 : > On 5/9/13 11:19 AM, David Hauweele wrote: >> >> 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. > > > >> Signed-off-by: David Hauweele >> --- >> 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) >> >