From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: [PATCH] smsc911x: add disable and re-enable Rx int to de-assert interrupt pin Date: Thu, 23 Dec 2010 18:43:13 +0800 Message-ID: <1293100993-3956-1-git-send-email-jason77.wang@gmail.com> Cc: netdev@vger.kernel.org, steve.glendinning@smsc.com, linux-omap@vger.kernel.org To: davem@davemloft.net Return-path: Received: from mail.windriver.com ([147.11.1.11]:50081 "EHLO mail.windriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752277Ab0LWKiZ (ORCPT ); Thu, 23 Dec 2010 05:38:25 -0500 Sender: netdev-owner@vger.kernel.org List-ID: When kernel enters irqhanlder, it will check the Rx interrupt status bit, if Rx status is set but can't call napi_schedule(), it will do nothing and directly return form irqhandler. This situation is prone to be produced when we repeatly call irqhandler through netpoll interface(i.e kgdboe connecting). This is a potential risk for those level triggered platforms(i.e ti_omap3evm), because if we don't handle Rx int and just return from irqhandler, the irq pin will be keeping asserted, the level triggered platforms will have no chance to jump out from the Rx irq. The whole system will hung into the irq subsystem. To solve it, we add a disable/re-enable Rx int operation for this situation, this operation can de-assert interrupt pin for this time and will leave the received data and status in the FIFO for later interrupts to handle. Signed-off-by: Jason Wang --- drivers/net/smsc911x.c | 18 ++++++++++++------ 1 files changed, 12 insertions(+), 6 deletions(-) diff --git a/drivers/net/smsc911x.c b/drivers/net/smsc911x.c index 64bfdae..dd6312f 100644 --- a/drivers/net/smsc911x.c +++ b/drivers/net/smsc911x.c @@ -1492,14 +1492,20 @@ static irqreturn_t smsc911x_irqhandler(int irq, void *dev_id) } if (likely(intsts & inten & INT_STS_RSFL_)) { - if (likely(napi_schedule_prep(&pdata->napi))) { - /* Disable Rx interrupts */ - temp = smsc911x_reg_read(pdata, INT_EN); - temp &= (~INT_EN_RSFL_EN_); - smsc911x_reg_write(pdata, INT_EN, temp); + /* Disable Rx interrupts first, if doesn't meet + * napi_schedule_prep(), we will re-enable Rx interrupts. This + * disable and re-enable pair operation can De-assert interrupt + * line and is more safer to those level triggered platforms. */ + temp = smsc911x_reg_read(pdata, INT_EN); + temp &= (~INT_EN_RSFL_EN_); + smsc911x_reg_write(pdata, INT_EN, temp); + + if (likely(napi_schedule_prep(&pdata->napi))) /* Schedule a NAPI poll */ __napi_schedule(&pdata->napi); - } else { + else { + temp |= INT_EN_RSFL_EN_; + smsc911x_reg_write(pdata, INT_EN, temp); SMSC_WARNING(RX_ERR, "napi_schedule_prep failed"); } -- 1.5.6.5