linux-kernel - RE: [PATCH v3 4/6] PCI: xilinx: Clear interrupt FIFO during probe

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Date:	Thu, 11 Feb 2016 06:20:42 +0000
From:	Bharat Kumar Gogada <bharat.kumar.gogada@...inx.com>
To:	Paul Burton <paul.burton@...tec.com>,
	"linux-mips@...ux-mips.org" <linux-mips@...ux-mips.org>
CC:	Michal Simek <michals@...inx.com>,
	Ravikiran Gummaluri <rgummal@...inx.com>,
	Soren Brinkmann <sorenb@...inx.com>,
	Jiang Liu <jiang.liu@...ux.intel.com>,
	Grygorii Strashko <grygorii.strashko@...com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Russell Joyce <russell.joyce@...k.ac.uk>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Thomas Gleixner" <tglx@...utronix.de>,
	Jingoo Han <jingoohan1@...il.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH v3 4/6] PCI: xilinx: Clear interrupt FIFO during probe

 > xilinx_pcie_init_port clears the pending interrupts in the interrupt decode
> register, but does not clear the interrupt FIFO. This would lead to spurious
> interrupts if any were present in the FIFO at probe time.
> Clear the interrupt FIFO prior to the interrupt decode register in order to
> start with a clean slate as expected.
> 
> Signed-off-by: Paul Burton <paul.burton@...tec.com>
> Fixes: 8961def56845 ("PCI: xilinx: Add Xilinx AXI PCIe Host Bridge IP driver")
> 
> ---
> 
> Changes in v3:
> - Split out from Boston patchset.
> 
> Changes in v2:
> - Add Fixes tag.
> 
>  drivers/pci/host/pcie-xilinx.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
> 
> diff --git a/drivers/pci/host/pcie-xilinx.c b/drivers/pci/host/pcie-xilinx.c index
> 1eb74a2..6c5a503 100644
> --- a/drivers/pci/host/pcie-xilinx.c
> +++ b/drivers/pci/host/pcie-xilinx.c
> @@ -568,6 +568,8 @@ static int xilinx_pcie_init_irq_domain(struct
> xilinx_pcie_port *port)
>   */
>  static void xilinx_pcie_init_port(struct xilinx_pcie_port *port)  {
> +	u32 val;
> +
>  	if (xilinx_pcie_link_is_up(port))
>  		dev_info(port->dev, "PCIe Link is UP\n");
>  	else
> @@ -577,6 +579,17 @@ static void xilinx_pcie_init_port(struct
> xilinx_pcie_port *port)
>  	pcie_write(port, ~XILINX_PCIE_IDR_ALL_MASK,
>  		   XILINX_PCIE_REG_IMR);
> 
> +	/* Clear interrupt FIFO */
> +	while (1) {
> +		val = pcie_read(port, XILINX_PCIE_REG_RPIFR1);
> +
> +		if (!(val & XILINX_PCIE_RPIFR1_INTR_VALID))
> +			break;
> +
> +		pcie_write(port, XILINX_PCIE_RPIFR1_ALL_MASK,
> +			   XILINX_PCIE_REG_RPIFR1);
> +	}
> +
Hi Paul,

This case will create problem with error case, suppose if we have continuous correctable errors on link this will always be while loop.

Bharat