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Message-ID: <1514336394-17747-2-git-send-email-honghui.zhang@mediatek.com> Date: Wed, 27 Dec 2017 08:59:53 +0800 From: <honghui.zhang@...iatek.com> To: <bhelgaas@...gle.com>, <matthias.bgg@...il.com>, <linux-arm-kernel@...ts.infradead.org>, <linux-mediatek@...ts.infradead.org>, <linux-pci@...r.kernel.org>, <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>, <yingjoe.chen@...iatek.com>, <eddie.huang@...iatek.com>, <ryder.lee@...iatek.com>, <lorenzo.pieralisi@....com> CC: <honghui.zhang@...iatek.com>, <hongkun.cao@...iatek.com>, <youlin.pei@...iatek.com>, <yong.wu@...iatek.com>, <yt.shen@...iatek.com>, <sean.wang@...iatek.com>, <xinping.qian@...iatek.com> Subject: [PATCH v5 1/2] PCI: mediatek: Clear IRQ status after IRQ dispatched to avoid reentry From: Honghui Zhang <honghui.zhang@...iatek.com> 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 infinite loop from step 2 to step 4. Clear the IRQ status after IRQ have been dispatched to avoid the IRQ reentry. This patch also fix another INTx IRQ issue by initialize the iterate before the loop. If an INTx IRQ re-occurred while we are dispatching the INTx IRQ, then iterate may start from PCI_NUM_INTX + INTX_SHIFT instead of INTX_SHIFT for the second time entering the for_each_set_bit_from() loop. Signed-off-by: Honghui Zhang <honghui.zhang@...iatek.com> Acked-by: Ryder Lee <ryder.lee@...iatek.com> --- drivers/pci/host/pcie-mediatek.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/drivers/pci/host/pcie-mediatek.c b/drivers/pci/host/pcie-mediatek.c index db93efd..fc29a9a 100644 --- a/drivers/pci/host/pcie-mediatek.c +++ b/drivers/pci/host/pcie-mediatek.c @@ -601,15 +601,16 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data) struct mtk_pcie_port *port = (struct mtk_pcie_port *)data; unsigned long status; u32 virq; - u32 bit = INTX_SHIFT; + u32 bit; while ((status = readl(port->base + PCIE_INT_STATUS)) & INTX_MASK) { + bit = INTX_SHIFT; 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 +620,10 @@ 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 */ -- 2.6.4
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