Re: [PATCH 0/5] drop low power policy board type

Mario Limonciello
2024-02-02T15:12:51Z

On 2/2/2024 07:13, Werner Fischer wrote:
> (adding Mario Limonciello in CC)
>
> On Thu, 2024-02-01 at 17:14 +0100, Niklas Cassel wrote:
>
>> This revives a patch sent out almost two years ago from Mario
>> Limonciello:
>> https://lore.kernel.org/linux-ide/20220524170508.563-1-mario.limonciello@amd.com/T/#u
>>
>> The reason why we did not merge it back then, is because LPM and
>> hotplug events are mutually exclusive.
>>
>> I've added a patch that checks if the port is external, i.e. either
>> hotplug capable or eSATA. For external ports, we never enable LPM, as
>> that will break hotplug.
>>
>> For ports that do not advertise themselves as external (typically
>> laptops), we set the LPM policy as requested.
>>
>> This matches how Microsoft Windows does things.
>> Thanks to Werner Fischer for suggesting something like this at last
>> year's ALPSS conference.
> Thank you for the discussions last year at the ALPSS and thanks a lot
> for implementing this now.
>
>> There might of course be some platform firmware that e.g. incorrectly
>> marks its port as internal, even though it is external, but if we
>> find any such platforms we will need to deal with them using quirks.
> I plan some testing within the upcoming two weeks.
> I'll do testing with the Elkhart-Lake based system (0x4b63 SATA
> controller) to verify whether LPM is activated.
> And I'll reach out to colleagues to test with hot-pluggable servers.
> Especially I'll try for them to get a system with an AMD 0x7901 SATA
> controller like Supermicro H12SSL-NT, as the default
> "board_ahci_mobile" for this SATA controller - see commit 1527f69204fe
> ("ata: ahci: Add Green Sardine vendor ID as board_ahci_mobile") - lead
> to Hot-Plug not working with default Ubuntu or Proxmox Kernels [1].
>
> As especially for AMD systems identical SATA controllers (like 0x7901
> in this case) can be used in both mobile systems and servers, Niklas'
> new patch series could could bring lasting improvement here.
>
> [1] https://www.thomas-krenn.com/en/wiki/AMD_EPYC_Server_with_Ubuntu_-_Enable_SATA_Hot-Swap
>
> --
> Best regards,
> Werner Fischer

Thanks for looping me in and also reviving the patch. The series looks
good to me. I do think that after this baked a bit and everyone is
happy we should also revisit changing the upstream default to match the
distros again too.

Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>