From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ryder Lee Subject: Re: [PATCH] PCI: Mediatek: clear irq status after irq dispathed to avoid reentry Date: Wed, 20 Dec 2017 11:08:15 +0800 Message-ID: <1513739295.18782.1.camel@mtkswgap22> References: <1513738334-26213-1-git-send-email-honghui.zhang@mediatek.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1513738334-26213-1-git-send-email-honghui.zhang-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: honghui.zhang-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org Cc: bhelgaas-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, matthias.bgg-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-mediatek-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, yingjoe.chen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org, eddie.huang-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org, hongkun.cao-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org, youlin.pei-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org, yong.wu-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org, yt.shen-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org, sean.wang-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org, xinping.qian-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org List-Id: devicetree@vger.kernel.org On Wed, 2017-12-20 at 10:52 +0800, honghui.zhang-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org wrote: > From: Honghui Zhang > > There maybe a same irq reentry scenario after irq received in current > irq handle flow: > EP device PCIe host driver EP driver > 1. issue an irq > 2. received irq > 3. clear irq status > 4. dispatch irq > 5. clear irq source > The irq status was not successfully cleared at step 2 since the irq > source was not cleared yet. So the PCIe host driver may receive the > same irq after step 5. Then there's an irq reentry occurred. > Even worse, if the reentry irq was not an irq that EP driver expected, > it may not handle the irq. Then we may run into the dead loop from > step 2 to step 4. > Clear the irq status after irq have been dispatched to avoid the irq > reentry. > > Signed-off-by: Honghui Zhang > --- > drivers/pci/host/pcie-mediatek.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/pci/host/pcie-mediatek.c b/drivers/pci/host/pcie-mediatek.c > index db93efd..3248771 100644 > --- a/drivers/pci/host/pcie-mediatek.c > +++ b/drivers/pci/host/pcie-mediatek.c > @@ -605,11 +605,11 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data) > > while ((status = readl(port->base + PCIE_INT_STATUS)) & INTX_MASK) { > for_each_set_bit_from(bit, &status, PCI_NUM_INTX + INTX_SHIFT) { > - /* Clear the INTx */ > - writel(1 << bit, port->base + PCIE_INT_STATUS); > virq = irq_find_mapping(port->irq_domain, > bit - INTX_SHIFT); > generic_handle_irq(virq); > + /* Clear the INTx */ > + writel(1 << bit, port->base + PCIE_INT_STATUS); > } > } > > @@ -619,10 +619,10 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data) > > while ((imsi_status = readl(port->base + PCIE_IMSI_STATUS))) { > for_each_set_bit(bit, &imsi_status, MTK_MSI_IRQS_NUM) { > - /* Clear the MSI */ > - writel(1 << bit, port->base + PCIE_IMSI_STATUS); > virq = irq_find_mapping(port->msi_domain, bit); > generic_handle_irq(virq); > + /* Clear the MSI */ > + writel(1 << bit, port->base + PCIE_IMSI_STATUS); > } > } > /* Clear MSI interrupt status */ Acked-by: Ryder Lee Thanks. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html