Re: [PATCH v3] ata: ahci: Disallow LPM for ASUSPRO-D840SA motherboard

[Damien Le Moal <dlemoal@kernel.org>]

On 6/12/25 23:17, Niklas Cassel wrote:
> A user has bisected a regression which causes graphical corruptions on his
> screen to commit 7627a0edef54 ("ata: ahci: Drop low power policy board
> type").
> 
> Simply reverting commit 7627a0edef54 ("ata: ahci: Drop low power policy
> board type") makes the graphical corruptions on his screen to go away.
> (Note: there are no visible messages in dmesg that indicates a problem
> with AHCI.)
> 
> The user also reports that the problem occurs regardless if there is an
> HDD or an SSD connected via AHCI, so the problem is not device related.
> 
> The devices also work fine on other motherboards, so it seems specific to
> the ASUSPRO-D840SA motherboard.
> 
> While enabling low power modes for AHCI is not supposed to affect
> completely unrelated hardware, like a graphics card, it does however
> allow the system to enter deeper PC-states, which could expose ACPI issues
> that were previously not visible (because the system never entered these
> lower power states before).
> 
> There are previous examples where enabling LPM exposed serious BIOS/ACPI
> bugs, see e.g. commit 240630e61870 ("ahci: Disable LPM on Lenovo 50 series
> laptops with a too old BIOS").
> 
> Since there hasn't been any BIOS update in years for the ASUSPRO-D840SA
> motherboard, disable LPM for this board, in order to avoid entering lower
> PC-states, which triggers graphical corruptions.
> 
> Cc: stable@vger.kernel.org
> Reported-by: Andy Yang <andyybtc79@gmail.com>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220111
> Fixes: 7627a0edef54 ("ata: ahci: Drop low power policy board type")
> Signed-off-by: Niklas Cassel <cassel@kernel.org>

Reviewed-by: Damien Le Moal <dlemoal@kernel.org>

-- 
Damien Le Moal
Western Digital Research