linux-kernel - [PATCH] pci: dwc: Clear MSI interrupt status after it is handled

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Message-ID: <1502364295-3786-1-git-send-email-faiz_abbas@ti.com>
Date:   Thu, 10 Aug 2017 16:54:55 +0530
From:   Faiz Abbas <faiz_abbas@...com>
To:     <jingoohan1@...il.com>, <Joao.Pinto@...opsys.com>
CC:     <bhelgaas@...gle.com>, <linux-pci@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, Faiz Abbas <faiz_abbas@...com>
Subject: [PATCH] pci: dwc: Clear MSI interrupt status after it is handled

If the interrupt status is cleared before it is handled, it is possible
that another interrupt will trigger while servicing the previous one.
This is causing timeouts in some wireless lan cards which use pcie.
Therefore, clear MSI interrupt status after it gets serviced instead
of before calling generic_handler.

Signed-off-by: Faiz Abbas <faiz_abbas@...com>
---
 drivers/pci/dwc/pcie-designware-host.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/dwc/pcie-designware-host.c b/drivers/pci/dwc/pcie-designware-host.c
index 28ed32b..78b2584 100644
--- a/drivers/pci/dwc/pcie-designware-host.c
+++ b/drivers/pci/dwc/pcie-designware-host.c
@@ -71,9 +71,9 @@ irqreturn_t dw_handle_msi_irq(struct pcie_port *pp)
 		while ((pos = find_next_bit((unsigned long *) &val, 32,
 					    pos)) != 32) {
 			irq = irq_find_mapping(pp->irq_domain, i * 32 + pos);
+			generic_handle_irq(irq);
 			dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_STATUS + i * 12,
 					    4, 1 << pos);
-			generic_handle_irq(irq);
 			pos++;
 		}
 	}
-- 
2.7.4