linux-kernel - Re: [PATCH v2 2/2] PCI: dra7xx: Iterate over INTx status bits

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Message-ID: <20180102154750.GA13516@red-moon>
Date:   Tue, 2 Jan 2018 15:47:50 +0000
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     Vignesh R <vigneshr@...com>
Cc:     Kishon Vijay Abraham I <kishon@...com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        linux-omap@...r.kernel.org, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] PCI: dra7xx: Iterate over INTx status bits

On Fri, Dec 29, 2017 at 05:11:31PM +0530, Vignesh R wrote:
> It is possible that more than one legacy IRQ may be set at the same
> time, therefore iterate and handle all the pending INTx interrupts
> before clearing the status and exiting the IRQ handler. Otherwise, some
> interrupts would be lost.
> 
> Signed-off-by: Vignesh R <vigneshr@...com>
> ---
>  drivers/pci/dwc/pci-dra7xx.c | 10 +++++++---
>  1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/dwc/pci-dra7xx.c b/drivers/pci/dwc/pci-dra7xx.c
> index 892f93910012..48c6ae535847 100644
> --- a/drivers/pci/dwc/pci-dra7xx.c
> +++ b/drivers/pci/dwc/pci-dra7xx.c
> @@ -257,7 +257,8 @@ static irqreturn_t dra7xx_pcie_msi_irq_handler(int irq, void *arg)
>  	struct dra7xx_pcie *dra7xx = arg;
>  	struct dw_pcie *pci = dra7xx->pci;
>  	struct pcie_port *pp = &pci->pp;
> -	u32 reg;
> +	unsigned long reg;
> +	u32 virq, bit;
>  
>  	reg = dra7xx_pcie_readl(dra7xx, PCIECTRL_DRA7XX_CONF_IRQSTATUS_MSI);
>  
> @@ -269,8 +270,11 @@ static irqreturn_t dra7xx_pcie_msi_irq_handler(int irq, void *arg)
>  	case INTB:
>  	case INTC:
>  	case INTD:
> -		generic_handle_irq(irq_find_mapping(dra7xx->irq_domain,
> -						    ffs(reg) - 1));
> +		for_each_set_bit(bit, &reg, PCI_NUM_INTX) {
> +			virq = irq_find_mapping(dra7xx->irq_domain, bit);
> +			if (virq)
> +				generic_handle_irq(virq);
> +		}
>  		break;
>  	}

It is not strictly related to this patch but why MSI and INTX are
handled as mutually exclusive in dra7xx_pcie_msi_irq_handler() ?

Lorenzo