linux-kernel - Re: [PATCH v17 09/12] PCI/AER: Allow clearing Error Status Register in FF mode

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Date:   Thu, 5 Mar 2020 21:45:46 -0800
From:   "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     bhelgaas@...gle.com
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        ashok.raj@...el.com
Subject: Re: [PATCH v17 09/12] PCI/AER: Allow clearing Error Status Register
 in FF mode



On 3/3/2020 6:36 PM, sathyanarayanan.kuppuswamy@...ux.intel.com wrote:
> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> 
> As per PCI firmware specification r3.2 System Firmware Intermediary
> (SFI) _OSC and DPC Updates ECR
> (https://members.pcisig.com/wg/PCI-SIG/document/13563), sec titled "DPC
> Event Handling Implementation Note", page 10, Error Disconnect Recover
> (EDR) support allows OS to handle error recovery and clearing Error
> Registers even in FF mode. So create new API pci_aer_raw_clear_status()
> which allows clearing AER registers without FF mode checks.
> 
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
> ---
>   drivers/pci/pci.h      |  2 ++
>   drivers/pci/pcie/aer.c | 22 ++++++++++++++++++----
>   2 files changed, 20 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
> index e57e78b619f8..c239e6dd2542 100644
> --- a/drivers/pci/pci.h
> +++ b/drivers/pci/pci.h
> @@ -655,6 +655,7 @@ extern const struct attribute_group aer_stats_attr_group;
>   void pci_aer_clear_fatal_status(struct pci_dev *dev);
>   void pci_aer_clear_device_status(struct pci_dev *dev);
>   int pci_cleanup_aer_error_status_regs(struct pci_dev *dev);
> +int pci_aer_raw_clear_status(struct pci_dev *dev);
>   #else
>   static inline void pci_no_aer(void) { }
>   static inline void pci_aer_init(struct pci_dev *d) { }
> @@ -665,6 +666,7 @@ static inline int pci_cleanup_aer_error_status_regs(struct pci_dev *dev)
>   {
>   	return -EINVAL;
>   }
> +int pci_aer_raw_clear_status(struct pci_dev *dev) { return -EINVAL; }
Its missing static specifier. It needs to be fixed. I can fix it in next 
version.
Bjorn, if there is no need for next version, can you please make this 
change ?
>   #endif
>   
>   #ifdef CONFIG_ACPI
> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
> index c0540c3761dc..41afefa562b7 100644
> --- a/drivers/pci/pcie/aer.c
> +++ b/drivers/pci/pcie/aer.c
> @@ -420,7 +420,16 @@ void pci_aer_clear_fatal_status(struct pci_dev *dev)
>   		pci_write_config_dword(dev, pos + PCI_ERR_UNCOR_STATUS, status);
>   }
>   
> -int pci_cleanup_aer_error_status_regs(struct pci_dev *dev)
> +/**
> + * pci_aer_raw_clear_status - Clear AER error registers.
> + * @dev: the PCI device
> + *
> + * NOTE: Allows clearing error registers in both FF and
> + * non FF modes.
> + *
> + * Returns 0 on success, or negative on failure.
> + */
> +int pci_aer_raw_clear_status(struct pci_dev *dev)
>   {
>   	int pos;
>   	u32 status;
> @@ -433,9 +442,6 @@ int pci_cleanup_aer_error_status_regs(struct pci_dev *dev)
>   	if (!pos)
>   		return -EIO;
>   
> -	if (pcie_aer_get_firmware_first(dev))
> -		return -EIO;
> -
>   	port_type = pci_pcie_type(dev);
>   	if (port_type == PCI_EXP_TYPE_ROOT_PORT) {
>   		pci_read_config_dword(dev, pos + PCI_ERR_ROOT_STATUS, &status);
> @@ -451,6 +457,14 @@ int pci_cleanup_aer_error_status_regs(struct pci_dev *dev)
>   	return 0;
>   }
>   
> +int pci_cleanup_aer_error_status_regs(struct pci_dev *dev)
> +{
> +	if (pcie_aer_get_firmware_first(dev))
> +		return -EIO;
> +
> +	return pci_aer_raw_clear_status(dev);
> +}
> +
>   void pci_save_aer_state(struct pci_dev *dev)
>   {
>   	struct pci_cap_saved_state *save_state;
> 

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer