6.15-stable review patch. If anyone has any objections, please let me know.
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From: Damien Le Moal dlemoal@kernel.org
[ Upstream commit 65b2c92f69d3df81422d27e5be012e357e733241 ]
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@kernel.org Reviewed-by: Hannes Reinecke hare@suse.de Reviewed-by: Niklas Cassel cassel@kernel.org Link: https://lore.kernel.org/r/20250701125321.69496-9-dlemoal@kernel.org Signed-off-by: Niklas Cassel cassel@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/ata/ahci.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c index 931da4749e80..f52ae776d990 100644 --- a/drivers/ata/ahci.c +++ b/drivers/ata/ahci.c @@ -1788,7 +1788,10 @@ static void ahci_update_initial_lpm_policy(struct ata_port *ap) if ((ap->host->flags & ATA_HOST_NO_PART) && (ap->host->flags & ATA_HOST_NO_SSC) && (ap->host->flags & ATA_HOST_NO_DEVSLP)) { - ata_port_dbg(ap, "no LPM states supported, not enabling LPM\n"); + ata_port_dbg(ap, + "No LPM states supported, forcing LPM max_power\n"); + ap->flags |= ATA_FLAG_NO_LPM; + ap->target_lpm_policy = ATA_LPM_MAX_POWER; return; }