On Tue, Jul 01, 2025 at 09:14:06AM +0900, Damien Le Moal wrote:
> Commit fa997b0576c9 ("ata: ahci: Do not enable LPM if no LPM states are
> supported by the HBA") introduced an early return in
> ahci_update_initial_lpm_policy() to ensure that the target_lpm_policy
> of ports belonging to a host that does not support the Partial, Slumber
> and DevSleep power states is unchanged and remains set to
> ATA_LPM_UNKNOWN and thus prevents the execution of
> ata_eh_link_set_lpm().
>
> However, a user or a system daemon (e.g. systemd-udevd) may still
> attempt changing the LPM policy through the sysfs
> link_power_management_policy of the host.
>
> Improve this to prevent sysfs LPM policy changes by setting the flag
> ATA_FLAG_NO_LPM for the port of such host, and initialize the port
> target_lpm_policy to ATA_LPM_MAX_POWER to guarantee that no unsupported
> low power state is being used on the port and its link.
>
> Signed-off-by: Damien Le Moal <dlemoal@xxxxxxxxxx>
Reviewed-by: Niklas Cassel <cassel@xxxxxxxxxx>
