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Message-ID: <e65c4fbb-95d0-5c5a-2b15-414b519d3319@redhat.com>
Date:   Fri, 25 Feb 2022 17:16:03 +0100
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Subject: Re: [PATCH v2 1/3] ata: ahci: Rename board_ahci_mobile
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To:     "Limonciello, Mario" <Mario.Limonciello@amd.com>,
        Christoph Hellwig <hch@infradead.org>
Cc:     Damien Le Moal <damien.lemoal@opensource.wdc.com>,
        "open list:LIBATA SUBSYSTEM (Serial and Parallel ATA drivers)" 
        <linux-ide@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>,
        "pmenzel@molgen.mpg.de" <pmenzel@molgen.mpg.de>
References: <20220225061113.223920-1-mario.limonciello@amd.com>
 <Yhj9Pdp/sHASmBw4@infradead.org>
 <BL1PR12MB5157D29423AE95EE32F00303E23E9@BL1PR12MB5157.namprd12.prod.outlook.com>
From:   Hans de Goede <hdegoede@redhat.com>
In-Reply-To: <BL1PR12MB5157D29423AE95EE32F00303E23E9@BL1PR12MB5157.namprd12.prod.outlook.com>
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Hi,

On 2/25/22 17:04, Limonciello, Mario wrote:
> [Public]
> 
>> On Fri, Feb 25, 2022 at 12:11:11AM -0600, Mario Limonciello wrote:
>>> This board definition was originally created for mobile devices to
>>> designate default link power managmeent policy to influence runtime
>>> power consumption.
>>>
>>> As this is interesting for more than just mobile designs, rename the
>>> board to `board_ahci_low_power` to make it clear it is about default
>>> policy.
>>
>> Is there any good reason to not just apply the policy to all devices
>> by default?
> 
> That sure would make this all cleaner.
> 
> I think Hans knows more of the history here than anyone else.  I had
> presumed there was some data loss scenarios with some of the older
> chipsets.

When I first introduced this change there were reports of crashes and
data corruption caused by setting the policy to min_power, these were
tied to some motherboards and/or to some drives.

This is the whole reason why I only enabled this on a subset of all the
AHCI chipsets.

At least on devices with a chipset which is currently marked as
mobile, the motherboard specific issues could be fixed with a BIOS
update. But I doubt that similar BIOS fixes have also been rolled
out to all desktop boards (and have been applied by all users),
and I also don't know about older boards.

So enabling this on all chipsets is definitely not without risks.

Regards,

Hans


> 
> Hans?
>