[PATCH v2 3/6] ata: Fix SATA_MOBILE_LPM_POLICY description in Kconfig

[Damien Le Moal <dlemoal@kernel.org>]

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@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Hannes Reinecke <hare@suse.de>
---
 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"
-- 
2.50.0