Re: [PATCH] ata: libata-core: Add ATA_QUIRK_NO_LPM_ON_ATI for certain Samsung SSDs

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

On 3/18/25 2:03 AM, Niklas Cassel wrote:
> Before commit 7627a0edef54 ("ata: ahci: Drop low power policy board type")
> the ATI AHCI controllers specified board type 'board_ahci' rather than
> board type 'board_ahci'. This means that LPM was historically not enabled
> for the ATI AHCI controllers.
> 
> By looking at commit 7a8526a5cd51 ("libata: Add ATA_HORKAGE_NO_NCQ_ON_ATI
> for Samsung 860 and 870 SSD."), it is clear that, for some unknown reason,
> that Samsung SSDs do not play nice with ATI AHCI controllers. (When using
> other AHCI controllers, NCQ can be enabled on these Samsung SSDs without
> issues.)
> 
> In a similar way, from user reports, it is clear the ATI AHCI controllers
> can enable LPM on e.g. Maxtor HDDs perfectly fine, but when enabling LPM
> on certain Samsung SSDs, things break. (E.g. the SSDs will not get detected
> by the ATI AHCI controller even after a COMRESET.)
> 
> Yet, when using LPM on these Samsung SSDs with other AHCI controllers, e.g.
> Intel AHCI controllers, these Samsung drives appear to work perfectly fine.
> 
> Considering that the combination of ATI + Samsung, for some unknown reason,
> does not seem to work well, disable LPM when detecting an ATI AHCI
> controller with a problematic Samsung SSD.
> 
> Apply this new ATA_QUIRK_NO_LPM_ON_ATI quirk for all Samsung SSDs that have
> already been reported to not play nice with ATI (ATA_QUIRK_NO_NCQ_ON_ATI).
> 
> Fixes: 7627a0edef54 ("ata: ahci: Drop low power policy board type")
> Reported-by: Eric <eric.4.debian@grabatoulnz.fr>
> Closes: https://lore.kernel.org/linux-ide/Z8SBZMBjvVXA7OAK@eldamar.lan/
> Signed-off-by: Niklas Cassel <cassel@kernel.org>

Looks OK to me.

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

-- 
Damien Le Moal
Western Digital Research