6.9-stable review patch. If anyone has any objections, please let me know.
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From: Niklas Cassel cassel@kernel.org
commit fa997b0576c9df635ee363406f5e014dba0f9264 upstream.
LPM consists of HIPM (host initiated power management) and DIPM (device initiated power management).
ata_eh_set_lpm() will only enable HIPM if both the HBA and the device supports it.
However, DIPM will be enabled as long as the device supports it. The HBA will later reject the device's request to enter a power state that it does not support (Slumber/Partial/DevSleep) (DevSleep is never initiated by the device).
For a HBA that doesn't support any LPM states, simply don't set a LPM policy such that all the HIPM/DIPM probing/enabling will be skipped.
Not enabling HIPM or DIPM in the first place is safer than relying on the device following the AHCI specification and respecting the NAK. (There are comments in the code that some devices misbehave when receiving a NAK.)
Performing this check in ahci_update_initial_lpm_policy() also has the advantage that a HBA that doesn't support any LPM states will take the exact same code paths as a port that is external/hot plug capable.
Side note: the port in ata_port_dbg() has not been given a unique id yet, but this is not overly important as the debug print is disabled unless explicitly enabled using dynamic debug. A follow-up series will make sure that the unique id assignment will be done earlier. For now, the important thing is that the function returns before setting the LPM policy.
Fixes: 7627a0edef54 ("ata: ahci: Drop low power policy board type") Cc: stable@vger.kernel.org Reviewed-by: Mario Limonciello mario.limonciello@amd.com Reviewed-by: Mika Westerberg mika.westerberg@linux.intel.com Reviewed-by: Damien Le Moal dlemoal@kernel.org Link: https://lore.kernel.org/r/20240618152828.2686771-2-cassel@kernel.org Signed-off-by: Niklas Cassel cassel@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/ata/ahci.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c index 07d66d2c5f0d..5eb38fbbbecd 100644 --- a/drivers/ata/ahci.c +++ b/drivers/ata/ahci.c @@ -1735,6 +1735,14 @@ static void ahci_update_initial_lpm_policy(struct ata_port *ap) if (ap->pflags & ATA_PFLAG_EXTERNAL) return;
+ /* 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) && + (ap->host->flags & ATA_HOST_NO_DEVSLP)) { + ata_port_dbg(ap, "no LPM states supported, not enabling LPM\n"); + return; + } + /* user modified policy via module param */ if (mobile_lpm_policy != -1) { policy = mobile_lpm_policy;