linux-kernel - Re: [PATCH v5 8/9] PCI/DPC: Add support for DPC recovery on NON

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Date:   Thu, 25 Jul 2019 10:50:37 -0600
From:   Keith Busch <kbusch@...nel.org>
To:     "sathyanarayanan.kuppuswamy@...ux.intel.com" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
Cc:     "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Raj, Ashok" <ashok.raj@...el.com>,
        "Busch, Keith" <keith.busch@...el.com>
Subject: Re: [PATCH v5 8/9] PCI/DPC: Add support for DPC recovery on
 NON_FATAL errors

On Tue, Jul 23, 2019 at 01:21:50PM -0700, sathyanarayanan.kuppuswamy@...ux.intel.com wrote:
> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> 
> Currently, in native mode, DPC driver is configured to trigger DPC only
> for FATAL errors and hence it only supports port recovery for FATAL
> errors. But with Error Disconnect Recover (EDR) support, DPC
> configuration is done by firmware, and hence we should expect DPC
> triggered for both FATAL/NON-FATAL errors. So add support for DPC
> recovery with NON-FATAL errors.
> 
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> ---
>  drivers/pci/pcie/dpc.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/pcie/dpc.c b/drivers/pci/pcie/dpc.c
> index 6e350149d793..5d328812aea9 100644
> --- a/drivers/pci/pcie/dpc.c
> +++ b/drivers/pci/pcie/dpc.c
> @@ -267,15 +267,20 @@ static void dpc_process_error(struct dpc_dev *dpc)
>  	/* show RP PIO error detail information */
>  	if (dpc->rp_extensions && reason == 3 && ext_reason == 0)
>  		dpc_process_rp_pio_error(dpc);
> -	else if (reason == 0 &&
> +	else if (reason <= 2 &&
>  		 dpc_get_aer_uncorrect_severity(pdev, &info) &&
>  		 aer_get_device_error_info(pdev, &info)) {
>  		aer_print_error(pdev, &info);
>  		pci_cleanup_aer_uncorrect_error_status(pdev);
> -		pci_aer_clear_fatal_status(pdev);
> +		if (reason != 1)
> +			pci_aer_clear_fatal_status(pdev);

I'm not quite sure I understand the above. If the reason is 1 or 2,
then the DSP received an error message from something downstream. In
otherwords, the port was notified an error occured somewhere, but it
was not the device that detected that error, so we should not expect
aer_print_error on that device to show anything useful. Right?

>  	}
>  
> -	/* We configure DPC so it only triggers on ERR_FATAL */
> +	/*
> +	 * Irrespective of whether the DPC event is triggered by
> +	 * ERR_FATAL or ERR_NONFATAL, since the link is already down,
> +	 * use the FATAL error recovery path for both cases.
> +	 */
>  	pcie_do_recovery(pdev, pci_channel_io_frozen, PCIE_PORT_SERVICE_DPC);
>  }
>  
> -- 
> 2.21.0
>