ata: ahci: Disable DIPM if host lacks support

The AHCI specification version 1.3.1 section 8.3.1.4 (Software
Requirements and Precedence) states that:

If CAP.SSC or CAP.PSC is cleared to ‘0’, software should disable
device-initiated power management by issuing the appropriate SET
FEATURES command to the device.

To satisfy this constraint and force ata_dev_configure to disable the
device DIPM feature, modify ahci_update_initial_lpm_policy() to set the
ATA_FLAG_NO_DIPM flag on ports that have a host with either the
ATA_HOST_NO_PART flag set or the ATA_HOST_NO_SSC flag set.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.de.>
Link: https://lore.kernel.org/r/20250701125321.69496-7-dlemoal@kernel.org
Signed-off-by: Niklas Cassel <cassel@kernel.org>

diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 1b4151d95888ded14763e3c4078fd1b219d56009..0760fa47d90eca974c419913b52bf2f46fc20cd3 100644 (file)
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -1780,6 +1780,13 @@ static void ahci_update_initial_lpm_policy(struct ata_port *ap)
                return;
        }
 
+       /* If no Partial or no Slumber, we cannot support DIPM. */
+       if ((ap->host->flags & ATA_HOST_NO_PART) ||
+           (ap->host->flags & ATA_HOST_NO_SSC)) {
+               ata_port_dbg(ap, "Host does not support DIPM\n");
+               ap->flags |= ATA_FLAG_NO_DIPM;
+       }
+
        /* If no LPM states are supported by the HBA, do not bother with LPM */
        if ((ap->host->flags & ATA_HOST_NO_PART) &&
            (ap->host->flags & ATA_HOST_NO_SSC) &&