linux-kernel - Re: [PATCH v9 5/8] PCI/AER: Allow clearing Error Status Register in FF mode

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Date:   Tue, 29 Oct 2019 16:17:58 -0700
From:   Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        ashok.raj@...el.com, keith.busch@...el.com
Subject: Re: [PATCH v9 5/8] PCI/AER: Allow clearing Error Status Register in
 FF mode


On 10/29/19 4:03 PM, Bjorn Helgaas wrote:
> On Tue, Oct 29, 2019 at 12:58:14PM -0700, Kuppuswamy Sathyanarayanan wrote:
>> On 10/28/19 4:22 PM, Bjorn Helgaas wrote:
>>> On Thu, Oct 03, 2019 at 04:39:01PM -0700, sathyanarayanan.kuppuswamy@...ux.intel.com wrote:
>>>> From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
>>>> @@ -430,9 +424,6 @@ 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);
>>>> @@ -455,7 +446,8 @@ void pci_aer_init(struct pci_dev *dev)
>>>>    	if (dev->aer_cap)
>>>>    		dev->aer_stats = kzalloc(sizeof(struct aer_stats), GFP_KERNEL);
>>>> -	pci_cleanup_aer_error_status_regs(dev);
>>>> +	if (!pcie_aer_get_firmware_first(dev))
>>>> +		pci_cleanup_aer_error_status_regs(dev);
>>> This effectively moves the "if (pcie_aer_get_firmware_first())" check
>>> from pci_cleanup_aer_error_status_regs() into one of the callers.  But
>>> there are two other callers: pci_aer_init() and pci_restore_state().
>>> Do they need the change, or do you want to cleanup the AER error
>>> registers there, but not here?
>> Good catch. I have added this check to pci_aer_init(). But it needs
>> to be added to pci_restore_state() as well. Instead of moving the
>> checks to the caller, If you agree, I could change the API to
>> pci_cleanup_aer_error_status_regs(struct pci_dev *dev, bool
>> skip_ff_check) and let the caller decide whether they want skip the
>> check or not.
> If all callers of pci_cleanup_aer_error_status_regs() would have to
> check pcie_aer_get_firmware_first(), I don't understand why you're
> moving the check at all.

We need exception for the call made from DPC driver. If 
pcie_aer_get_firmware_first()
call is made from DPC driver during EDR mode execution, then FF mode 
check needs
to be skipped.

>
-- 
Sathyanarayanan Kuppuswamy
Linux kernel developer