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Date: Tue, 30 Jan 2024 12:13:35 +0200
From: Mika Westerberg <mika.westerberg@linux.intel.com>
To: Jian-Hong Pan <jhp@endlessos.org>
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
Subject: Re: [PATCH 1/2] ata: ahci: Add force LPM policy quirk for ASUS
 B1400CEAE
Message-ID: <20240130101335.GU2543524@black.fi.intel.com>
References: <20240130095933.14158-1-jhp@endlessos.org>
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In-Reply-To: <20240130095933.14158-1-jhp@endlessos.org>

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.