Re: [PATCH 1/2] ata: ahci: Add force LPM policy quirk for ASUS B1400CEAE

[Jian-Hong Pan]

Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> 於 2024年1月30日 週二 下午6:13寫道：
>
> Hi,
>
> On Tue, Jan 30, 2024 at 05:59:33PM +0800, Jian-Hong Pan wrote:
> > Some systems, like ASUS B1400CEAE equipped with the SATA controller
> > [8086:a0d3] can use LPM policy to save power, especially for s2idle.
> >
> > However, the same controller may be failed on other platforms. So,
> > commit (ata: ahci: Revert "ata: ahci: Add Tiger Lake UP{3,4} AHCI
> > controller") drops LPM policy for [8086:a0d3]. But, this blocks going
> > to deeper CPU Package C-state when s2idle with enabled Intel VMD.
>
> Tiger Lake really should support this with no issues (as are the
> generations after it). I suggest trying to figure out what was the root
> cause of the original problem that triggered the revert, if possible at
> all, perhaps it is is something not related to LPM and that would allow
> us to enable this unconditionally on all Tiger Lake.
>
> I'm pretty sure the platform where this was reported suffers the same
> s2idle issue you are seeing without this patch.

Simply applying LPM policy to [8086:a0d3] sounds like a good idea!

I installed an SATA storage into ASUS B1400CEAE and tested with
enabled & disabled VMD again. Both the NVMe and SATA storage work with
applying LPM policy to [8086:a0d3], which means that it does not hit
the issue mentioned in the commit (ata: ahci: Revert "ata: ahci: Add
Tiger Lake UP{3,4} AHCI controller").

Jian-Hong Pan