linux-kernel - RE: [PATCH v3 2/6] PCI: xilinx: Unify INTx & MSI interrupt FIFO decode

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Message-ID: <8520D5D51A55D047800579B09414719825881ADE@XAP-PVEXMBX01.xlnx.xilinx.com>
Date:	Thu, 11 Feb 2016 05:42:30 +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>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Grygorii Strashko <grygorii.strashko@...com>,
	Russell Joyce <russell.joyce@...k.ac.uk>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Rob Herring <robh@...nel.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 2/6] PCI: xilinx: Unify INTx & MSI interrupt FIFO
 decode

> Subject: [PATCH v3 2/6] PCI: xilinx: Unify INTx & MSI interrupt FIFO decode
> 
> When decoding either an INTx or MSI interrupt, the driver has no way to
> know which it will pull out of the interrupt FIFO. If both were pending then
> this would lead to either the interrupt being handled incorrectly (MSI
> interrupt treated as INTx) or not at all (INTx interrupt dropped by MSI path).
> Unify the reading of the interrupt FIFO & act according to the type of
> interrupt actually read.
> 
> 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 | 47 +++++++++++++-----------------------------
>  1 file changed, 14 insertions(+), 33 deletions(-)
> 
> diff --git a/drivers/pci/host/pcie-xilinx.c b/drivers/pci/host/pcie-xilinx.c index
> 1490bd1..afdfb09 100644
> --- a/drivers/pci/host/pcie-xilinx.c
> +++ b/drivers/pci/host/pcie-xilinx.c
> @@ -397,7 +397,7 @@ static const struct irq_domain_ops intx_domain_ops
> = {  static irqreturn_t xilinx_pcie_intr_handler(int irq, void *data)  {
>  	struct xilinx_pcie_port *port = (struct xilinx_pcie_port *)data;
> -	u32 val, mask, status, msi_data;
> +	u32 val, mask, status;
> 
>  	/* Read interrupt decode and mask registers */
>  	val = pcie_read(port, XILINX_PCIE_REG_IDR); @@ -437,8 +437,8 @@
> static irqreturn_t xilinx_pcie_intr_handler(int irq, void *data)
>  		xilinx_pcie_clear_err_interrupts(port);
>  	}
> 
> -	if (status & XILINX_PCIE_INTR_INTX) {
> -		/* INTx interrupt received */
> +	if (status & (XILINX_PCIE_INTR_INTX | XILINX_PCIE_INTR_MSI)) {
> +		/* Interrupt received */
>  		val = pcie_read(port, XILINX_PCIE_REG_RPIFR1);
> 
>  		/* Check whether interrupt valid */
> @@ -447,41 +447,22 @@ static irqreturn_t xilinx_pcie_intr_handler(int irq,
> void *data)
>  			return IRQ_HANDLED;
>  		}
> 
> -		if (!(val & XILINX_PCIE_RPIFR1_MSI_INTR)) {
> -			/* Clear interrupt FIFO register 1 */
> -			pcie_write(port, XILINX_PCIE_RPIFR1_ALL_MASK,
> -				   XILINX_PCIE_REG_RPIFR1);
> -
> -			/* Handle INTx Interrupt */
> +		if (val & XILINX_PCIE_RPIFR1_MSI_INTR) {
> +			irq = pcie_read(port, XILINX_PCIE_REG_RPIFR2) &
> +				XILINX_PCIE_RPIFR2_MSG_DATA;
> +		} else {
>  			val = ((val & XILINX_PCIE_RPIFR1_INTR_MASK) >>
>  				XILINX_PCIE_RPIFR1_INTR_SHIFT) + 1;
> -			generic_handle_irq(irq_find_mapping(port-
> >irq_domain,
> -							    val));
> +			irq = irq_find_mapping(port->irq_domain, val);
>  		}
> -	}
> 
> -	if (status & XILINX_PCIE_INTR_MSI) {
> -		/* MSI Interrupt */
> -		val = pcie_read(port, XILINX_PCIE_REG_RPIFR1);
> +		/* Clear interrupt FIFO register 1 */
> +		pcie_write(port, XILINX_PCIE_RPIFR1_ALL_MASK,
> +			   XILINX_PCIE_REG_RPIFR1);
> 
> -		if (!(val & XILINX_PCIE_RPIFR1_INTR_VALID)) {
> -			dev_warn(port->dev, "RP Intr FIFO1 read error\n");
> -			return IRQ_HANDLED;
> -		}
> -
> -		if (val & XILINX_PCIE_RPIFR1_MSI_INTR) {
> -			msi_data = pcie_read(port,
> XILINX_PCIE_REG_RPIFR2) &
> -				   XILINX_PCIE_RPIFR2_MSG_DATA;
> -
> -			/* Clear interrupt FIFO register 1 */
> -			pcie_write(port, XILINX_PCIE_RPIFR1_ALL_MASK,
> -				   XILINX_PCIE_REG_RPIFR1);
> -
> -			if (IS_ENABLED(CONFIG_PCI_MSI)) {
> -				/* Handle MSI Interrupt */
> -				generic_handle_irq(msi_data);
> -			}
> -		}
> +		if (IS_ENABLED(CONFIG_PCI_MSI) ||
> +			!(val & XILINX_PCIE_RPIFR1_MSI_INTR))
> +			generic_handle_irq(irq);
>  	}
> 
>  	if (status & XILINX_PCIE_INTR_SLV_UNSUPP)
> --

Hi Paul,

Even with above condition you are still missing either MSI or legacy interrupt handling, when both MSI and legacy interrupts occurred.

Bharat