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From: Jian-Hong Pan <jhp@endlessos.org>
Date: Wed, 31 Jan 2024 16:56:27 +0800
Message-ID: <CAPpJ_ef4KuZzBaMupH-iW0ricyY_9toa7A4rB2vyeaFu7ROiDA@mail.gmail.com>
Subject: Re: [PATCH 1/2] ata: ahci: Add force LPM policy quirk for ASUS B1400CEAE
To: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: David Box <david.e.box@linux.intel.com>, Damien Le Moal <dlemoal@kernel.org>, 
	Niklas Cassel <cassel@kernel.org>, Nirmal Patel <nirmal.patel@linux.intel.com>, 
	Jonathan Derrick <jonathan.derrick@linux.dev>, linux-ide@vger.kernel.org, 
	linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, linux@endlessos.org
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Mika Westerberg <mika.westerberg@linux.intel.com> =E6=96=BC 2024=E5=B9=B41=
=E6=9C=8830=E6=97=A5 =E9=80=B1=E4=BA=8C =E4=B8=8B=E5=8D=886:13=E5=AF=AB=E9=
=81=93=EF=BC=9A
>
> 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