linux-kernel - Re: [PATCHv5 10/20] PCI: mobiveil: Fix the INTx process errors

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Date:   Wed, 12 Jun 2019 16:08:20 +0100
From:   Lorenzo Pieralisi <lorenzo.pieralisi@....com>
To:     "Z.q. Hou" <zhiqiang.hou@....com>,
        Karthikeyan Mitran <m.karthikeyan@...iveil.co.in>
Cc:     "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "l.subrahmanya@...iveil.co.in" <l.subrahmanya@...iveil.co.in>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        Leo Li <leoyang.li@....com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will.deacon@....com" <will.deacon@....com>,
        Mingkai Hu <mingkai.hu@....com>,
        "M.h. Lian" <minghuan.lian@....com>,
        Xiaowei Bao <xiaowei.bao@....com>
Subject: Re: [PATCHv5 10/20] PCI: mobiveil: Fix the INTx process errors

On Fri, Apr 12, 2019 at 08:36:12AM +0000, Z.q. Hou wrote:
> From: Hou Zhiqiang <Zhiqiang.Hou@....com>
> 
> In the loop block, there is not code to update the loop key,
> this patch updates the loop key by re-read the INTx status
> register.
> 
> This patch also add the clearing of the handled INTx status.
> 
> Note: Need MV to test this fix.

This means INTX were never tested and current code handling them is,
AFAICS, an infinite loop which is very very bad.

This is a gross bug and must be fixed as soon as possible.

I want Karthikeyan ACK and Tested-by on this patch.

Lorenzo

> Fixes: 9af6bcb11e12 ("PCI: mobiveil: Add Mobiveil PCIe Host Bridge IP driver")
> Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@....com>
> Reviewed-by: Minghuan Lian <Minghuan.Lian@....com>
> Reviewed-by: Subrahmanya Lingappa <l.subrahmanya@...iveil.co.in>
> ---
> V5:
>  - Corrected and retouched the subject and changelog.
> 
>  drivers/pci/controller/pcie-mobiveil.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/controller/pcie-mobiveil.c b/drivers/pci/controller/pcie-mobiveil.c
> index 4ba458474e42..78e575e71f4d 100644
> --- a/drivers/pci/controller/pcie-mobiveil.c
> +++ b/drivers/pci/controller/pcie-mobiveil.c
> @@ -361,6 +361,7 @@ static void mobiveil_pcie_isr(struct irq_desc *desc)
>  	/* Handle INTx */
>  	if (intr_status & PAB_INTP_INTX_MASK) {
>  		shifted_status = csr_readl(pcie, PAB_INTP_AMBA_MISC_STAT);
> +		shifted_status &= PAB_INTP_INTX_MASK;
>  		shifted_status >>= PAB_INTX_START;
>  		do {
>  			for_each_set_bit(bit, &shifted_status, PCI_NUM_INTX) {
> @@ -372,12 +373,16 @@ static void mobiveil_pcie_isr(struct irq_desc *desc)
>  					dev_err_ratelimited(dev, "unexpected IRQ, INT%d\n",
>  							    bit);
>  
> -				/* clear interrupt */
> -				csr_writel(pcie,
> -					   shifted_status << PAB_INTX_START,
> +				/* clear interrupt handled */
> +				csr_writel(pcie, 1 << (PAB_INTX_START + bit),
>  					   PAB_INTP_AMBA_MISC_STAT);
>  			}
> -		} while ((shifted_status >> PAB_INTX_START) != 0);
> +
> +			shifted_status = csr_readl(pcie,
> +						   PAB_INTP_AMBA_MISC_STAT);
> +			shifted_status &= PAB_INTP_INTX_MASK;
> +			shifted_status >>= PAB_INTX_START;
> +		} while (shifted_status != 0);
>  	}
>  
>  	/* read extra MSI status register */
> -- 
> 2.17.1
>