Re: [PATCH 1/2] PCI/AER: Do not reset the device status if doing firmware first handling.

["Kuppuswamy, Sathyanarayanan" <sathyanarayanan.kuppuswamy@linux.intel.com>]

Hi Jonathan,

On 6/16/20 10:47 AM, Bjorn Helgaas wrote:
> [+cc Sathy]
> 
> On Fri, May 22, 2020 at 01:31:33AM +0800, Jonathan Cameron wrote:
>> pci_aer_clear_device_status() currently resets the device status even when
>> firmware first handling is going on.  In particular it resets it on the
>> root port.
>>
>> This has been discussed previously
>> https://lore.kernel.org/patchwork/patch/427375/.
pci_aer_clear_device_status() is only used by handle_error_source(). And
I don't think handle_error_source() is called in FF mode. Can you
give more details on this issue ?
> 
> I don't think this reference is really pertinent, is it?  That patch
> to b2c8881da764 changes pci_cleanup_aer_uncorrect_error_status() so it
> doesn't clear PCI_ERR_UNCOR_STATUS in "firmware-first" mode.
> 
> But your patch only affects PCI_EXP_DEVSTA, not PCI_ERR_UNCOR_STATUS.
> 
>> Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
>> ---
>>   drivers/pci/pcie/aer.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c
>> index f4274d301235..43e78b97ace6 100644
>> --- a/drivers/pci/pcie/aer.c
>> +++ b/drivers/pci/pcie/aer.c
>> @@ -373,6 +373,9 @@ void pci_aer_clear_device_status(struct pci_dev *dev)
>>   {
>>   	u16 sta;
>>   
>> +	if (pcie_aer_get_firmware_first(dev))
>> +		return;
> 
> This needs to be adjusted because pcie_aer_get_firmware_first() no
> longer exists after 708b20003624 ("PCI/AER: Remove HEST/FIRMWARE_FIRST
> parsing for AER ownership").
> 
> This will use the _OSC AER ownership bit to gate clearing of the
> status bits in the PCIe capability (not the AER capability).
> 
> I think that's the right thing to do, but it's certainly not obvious
> from the _OSC description in the PCI Firmware Spec r3.2.  I think we
> need a pointer to the ECN that clarifies this, i.e., sec 4.5.1 of:
> 
>    System Firmware Intermediary (SFI) _OSC and DPC Updates ECN, Feb 24,
>    2020, affecting PCI Firmware Specification, Rev. 3.2
>    https://members.pcisig.com/wg/PCI-SIG/document/14076
> 
>>   	pcie_capability_read_word(dev, PCI_EXP_DEVSTA, &sta);
>>   	pcie_capability_write_word(dev, PCI_EXP_DEVSTA, sta);
>>   }
>> -- 
>> 2.19.1
>>

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer