Re: [PATCH v2 2/2] PCI / ACPI: PCI delay optimization from ACPI

[Aaron Lu <aaron.lu@intel.com>]

On 03/24/2015 10:08 PM, Bjorn Helgaas wrote:
> On Tue, Mar 24, 2015 at 05:04:58PM +0800, Aaron Lu wrote:
>> @@ -575,6 +637,9 @@ static void pci_acpi_setup(struct device *dev)
>>  	if (!adev)
>>  		return;
>>  
>> +	if (pci_dev->pm_cap)
>> +		pci_acpi_delay_optimize(pci_dev, adev->handle);
> 
> Is the "pm_cap" test really necessary?  If we do it this way, we then have
> to convince ourselves that pdev->d3cold_delay and pdev->d3_delay are only
> needed when pdev has a pm_cap.
> 
> If we *always* fill in the delay values, it's possible they won't be used,
> but we don't have to prove any connection between them and a pm_cap, so
> the code is easier to analyze.

I remembered why I did the pm_cap test: the d3cold_delay and d3_delay is
only filled when pm_cap is set in pci_pm_init - if the device doesn't
have PCI_CAP_ID_PM set, its pm_cap will be 0 and d3cold_delay, d3_delay
will not be assigned.