linux-kernel - Re: [PATCH] PCI: DPC: Clear AER status bits before disabling port containment

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Message-ID: <605540c0-b6c5-89a2-9d50-12a3005d9f88@codeaurora.org>
Date:   Wed, 16 May 2018 18:44:22 -0400
From:   Sinan Kaya <okaya@...eaurora.org>
To:     Alexandru Gagniuc <mr.nuke.me@...il.com>, bhelgaas@...gle.com
Cc:     alex_gagniuc@...lteam.com, austin_bolen@...l.com,
        shyam_iyer@...l.com, Keith Busch <keith.busch@...el.com>,
        Dongdong Liu <liudongdong3@...wei.com>,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: DPC: Clear AER status bits before disabling port
 containment

On 5/16/2018 5:33 PM, Alexandru Gagniuc wrote:
> AER status bits are sticky, and they survive system resets. Downstream
> devices are usually taken care of after re-enumerating the downstream
> busses, as the AER bits are cleared during probe().
> 
> However, nothing clears the bits of the port which contained the
> error. These sticky bits may leave some BIOSes to think that something
> bad happened, and print ominous messages on next boot. To prevent this,
> tidy up the AER status bits before releasing containment.
> 
> Signed-off-by: Alexandru Gagniuc <mr.nuke.me@...il.com>
> ---
>  drivers/pci/pcie/dpc.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> index 8c57d607e603..bf82d6936556 100644
> --- a/drivers/pci/pcie/dpc.c
> +++ b/drivers/pci/pcie/dpc.c
> @@ -112,6 +112,10 @@ static void dpc_work(struct work_struct *work)
>  		dpc->rp_pio_status = 0;
>  	}
>  
> +	/* DPC event made a mess of our AER status bits. Clean them up. */
> +	pci_cleanup_aer_error_status_regs(pdev);
> +	/* TODO: Should we also use aer_print_error to log the event? */
> +
>  	pci_write_config_word(pdev, cap + PCI_EXP_DPC_STATUS,
>  		PCI_EXP_DPC_STATUS_TRIGGER | PCI_EXP_DPC_STATUS_INTERRUPT);
>  
> 

I think Keith has a patch to fix this. It was under review at some point.

-- 
Sinan Kaya
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.