Re: [PATCH] PCI/PM: Put devices to low power state on shutdown

[Mario Limonciello <mario.limonciello@amd.com>]

On 8/22/2024 14:28, Mario Limonciello wrote:
> On 7/12/2024 01:24, Kai-Heng Feng wrote:
>> Some laptops wake up after poweroff when HP Thunderbolt Dock G4 is
>> connected.
>>
>> The following error message can be found during shutdown:
>> pcieport 0000:00:1d.0: AER: Correctable error message received from 
>> 0000:09:04.0
>> pcieport 0000:09:04.0: PCIe Bus Error: severity=Correctable, type=Data 
>> Link Layer, (Receiver ID)
>> pcieport 0000:09:04.0:   device [8086:0b26] error 
>> status/mask=00000080/00002000
>> pcieport 0000:09:04.0:    [ 7] BadDLLP
>>
>> Calling aer_remove() during shutdown can quiesce the error message,
>> however the spurious wakeup still happens.
>>
>> The issue won't happen if the device is in D3 before system shutdown, so
>> putting device to low power state before shutdown to solve the issue.
>>
>> I don't have a sniffer so this is purely guesswork, however I believe
>> putting device to low power state it's the right thing to do.
> 
> KH,
> 
> I did testing with your patch along with a few others, and found that it 
> does the best job to put a majority of devices into a low power state 
> properly.
> 
> I have the details of what happens at S5 outlined on this Gist:
> https://gist.github.com/superm1/f8f81e52f5b1d55b64493fdaec38e31c
> 
> * KH column is this patch.
> * ML column is 
> https://lore.kernel.org/linux-usb/43594a1c-c0dd-4ae1-b2c4-f5198e3fe951@amd.com/T/#m03d0b36f86fb4722009b24a8ee547011128db80b
> * FS column is 0fab972eef49 being applied again
> 
> I also have power testing data from an OEM's system that shows that it 
> improves things well enough that a previously failing energy star 
> certification is now passing.
> 
> Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
> Tested-by: Mario Limonciello <mario.limonciello@amd.com>

Bjorn,

As we're getting close to the merge window, any thoughts about this patch?

Thanks,

> 
>>
>> Link: https://bugzilla.kernel.org/show_bug.cgi?id=219036
>> Signed-off-by: Kai-Heng Feng <kai.heng.feng@canonical.com>
>> ---
>>   drivers/pci/pci-driver.c | 8 ++++++++
>>   1 file changed, 8 insertions(+)
>>
>> diff --git a/drivers/pci/pci-driver.c b/drivers/pci/pci-driver.c
>> index af2996d0d17f..4c6f66f3eb54 100644
>> --- a/drivers/pci/pci-driver.c
>> +++ b/drivers/pci/pci-driver.c
>> @@ -510,6 +510,14 @@ static void pci_device_shutdown(struct device *dev)
>>       if (drv && drv->shutdown)
>>           drv->shutdown(pci_dev);
>> +    /*
>> +     * If driver already changed device's power state, it can mean the
>> +     * wakeup setting is in place, or a workaround is used. Hence 
>> keep it
>> +     * as is.
>> +     */
>> +    if (!kexec_in_progress && pci_dev->current_state == PCI_D0)
>> +        pci_prepare_to_sleep(pci_dev);
>> +
>>       /*
>>        * If this is a kexec reboot, turn off Bus Master bit on the
>>        * device to tell it to not continue to do DMA. Don't touch
>