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Date:   Thu, 18 Aug 2022 21:51:21 +0200
From:   Andrew Lunn <andrew@lunn.ch>
To:     Pali =?iso-8859-1?Q?Roh=E1r?= <pali@kernel.org>
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Rob Herring <robh+dt@kernel.org>,
        Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>,
        Gregory Clement <gregory.clement@bootlin.com>,
        Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
        linux-pci@vger.kernel.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 2/4] PCI: mvebu: Implement support for interrupts on
 emulated bridge
Message-ID: <Yv6YOZ2FuTn8D5qS@lunn.ch>
References: <20220817230036.817-1-pali@kernel.org>
 <20220817230036.817-3-pali@kernel.org>
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> -static irqreturn_t mvebu_pcie_irq_handler(int irq, void *arg)
> +static irqreturn_t mvebu_pcie_error_irq_handler(int irq, void *arg)
> +{
> +	struct mvebu_pcie_port *port = arg;
> +	struct device *dev = &port->pcie->pdev->dev;
> +	u32 cause, unmask, status;
> +
> +	cause = mvebu_readl(port, PCIE_INT_CAUSE_OFF);
> +	unmask = mvebu_readl(port, PCIE_INT_UNMASK_OFF);
> +	status = cause & unmask;
> +
> +	/* "error" interrupt handler does not process INTX interrupts */
> +	status &= ~(PCIE_INT_INTX(0) | PCIE_INT_INTX(1) |
> +		    PCIE_INT_INTX(2) | PCIE_INT_INTX(3));

Just for my understanding...

There are two interrupts, but the status information what those
interrupts actually mean are all packed into one register? I assume
reading the clause register does not clear set bits? Otherwise there
would be a race condition. Are these actually level interrupts, and in
order to clear them you need to poke some other register?

> +	/*
> +	 * Old DT bindings do not contain "error" interrupt
> +	 * so do not fail probing driver when interrupt does not exist.
> +	 */
> +	port->error_irq = of_irq_get_byname(child, "error");
> +	if (port->error_irq == -EPROBE_DEFER) {
> +		ret = port->error_irq;
> +		goto err;
> +	}
> +	if (port->error_irq <= 0) {
> +		dev_warn(dev, "%s: interrupts on Root Port are unsupported, "

Maybe that should be "Error interrupts on Root..." ?

      Andrew