On 6/27/25 15:03, Hannes Reinecke wrote:
> On 6/27/25 03:11, Damien Le Moal wrote:
>> Improve the description of the possible default SATA link power
>> management policies and add the missing description for policy 5.
>> No functional changes.
>>
>> Fixes: a5ec5a7bfd1f ("ata: ahci: Support state with min power but Partial low power state")
>> Cc: stable@xxxxxxxxxxxxxxx
>> Signed-off-by: Damien Le Moal <dlemoal@xxxxxxxxxx>
>> ---
>> drivers/ata/Kconfig | 36 ++++++++++++++++++++++++++----------
>> 1 file changed, 26 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/ata/Kconfig b/drivers/ata/Kconfig
>> index e00536b49552..1d53d7b568bd 100644
>> --- a/drivers/ata/Kconfig
>> +++ b/drivers/ata/Kconfig
>> @@ -117,23 +117,39 @@ config SATA_AHCI
>>
>> config SATA_MOBILE_LPM_POLICY
>> int "Default SATA Link Power Management policy"
>> - range 0 4
>> + range 0 5
>> default 3
>> depends on SATA_AHCI
>> help
>> Select the Default SATA Link Power Management (LPM) policy to use
>> for chipsets / "South Bridges" supporting low-power modes. Such
>> chipsets are ubiquitous across laptops, desktops and servers.
>> -
>> - The value set has the following meanings:
>> + Each policy combines power saving states and features:
>> + - Partial: The Phy logic is powered but is in a reduced power
>> + state. The exit latency from this state is no longer than
>> + 10us).
>> + - Slumber: The Phy logic is powered but is in an even lower power
>> + state. The exit latency from this state is potentially
>> + longer, but no longer than 10ms.
>> + - DevSleep: The Phy logic may be powered down. The exit latency from
>> + this state is no longer than 20 ms, unless otherwise
>> + specified by DETO in the device Identify Device Data log.
>> + - HIPM: Host Initiated Power Management (host automatic transisitons
>> + to partial and slumber).
>> + - DIPM: Device Initiated Power Management (device automatic
>> + transitions to partial and slumber).
>> +
>> + The possible values for the default SATA link power management
>> + policies are:
>> 0 => Keep firmware settings
>> - 1 => Maximum performance
>> - 2 => Medium power
>> - 3 => Medium power with Device Initiated PM enabled
>> - 4 => Minimum power
>> -
>> - Note "Minimum power" is known to cause issues, including disk
>> - corruption, with some disks and should not be used.
>> + 1 => No power savings (maximum performance)
>> + 2 => HIPM (Partial)
>> + 3 => HIPM (Partial) and DIPM (Partial and Slumber)
>> + 4 => HIPM (Partial and DevSleep) and DIPM (Partial and Slumber)
>> + 5 => HIPM (Slumber and DevSleep) and DIPM (Partial and Slumber)
>> +
>> + Excluding the value 0, higher values represent policies with higher
>> + power savings.
>>
>> config SATA_AHCI_PLATFORM
>> tristate "Platform AHCI SATA support"
>
> Hmm. Isn't it worth creating an official documentation somewhere in
> Documentation/* to have this available without having to look at the
> source code?
Yes, I am considering this.
I did not write it in the cover letter, but these patches are the first part of
a much bigger patch series that addresses a lot of LPM issues that we recently
discovered doing completely unrelated tests. Once that is out, documenting
everything will be a good thing to do.
>
> Otherwise:
> Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
>
> Cheers,
>
> Hannes
--
Damien Le Moal
Western Digital Research
