Re: [PATCH] ata: libata-core: Add ATA_HORKAGE_NOLPM for Apacer AS340

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On Thu, May 30, 2024 at 11:27:04PM +0200, Niklas Cassel wrote:
> Commit 7627a0edef54 ("ata: ahci: Drop low power policy board type")
> dropped the board_ahci_low_power board type, and instead enables LPM if:
> -The AHCI controller reports that it supports LPM (Partial/Slumber), and
> -CONFIG_SATA_MOBILE_LPM_POLICY != 0, and
> -The port is not defined as external in the per port PxCMD register, and
> -The port is not defined as hotplug capable in the per port PxCMD
>  register.
> 
> Partial and Slumber LPM states can either be initiated by HIPM or DIPM.
> 
> For HIPM (host initiated power management) to get enabled, both the AHCI
> controller and the drive have to report that they support HIPM.
> 
> For DIPM (device initiated power management) to get enabled, only the
> drive has to report that it supports DIPM. However, the HBA will reject
> device requests to enter LPM states which the HBA does not support.
> 
> The problem is that Apacer AS340 drives do not handle low power modes
> correctly. The problem was most likely not seen before because no one
> had used this drive with a AHCI controller with LPM enabled.
> 
> Add a quirk so that we do not enable LPM for this drive, since we see
> command timeouts if we do (even though the drive claims to support DIPM).
> 
> Fixes: 7627a0edef54 ("ata: ahci: Drop low power policy board type")
> Cc: stable@vger.kernel.org
> Reported-by: Tim Teichmann <teichmanntim@outlook.de>
> Closes: https://lore.kernel.org/linux-ide/87bk4pbve8.ffs@tglx/
> Signed-off-by: Niklas Cassel <cassel@kernel.org>

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>