[PATCH 5.4.y] ata: Fix SATA_MOBILE_LPM_POLICY description in Kconfig

[Sasha Levin <sashal@kernel.org>]

From: Damien Le Moal <dlemoal@kernel.org>

[ Upstream commit ed62a62a18bc144f73eadf866ae46842e8f6606e ]

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>
Reviewed-by: Niklas Cassel <cassel@kernel.org>
[ Adjust context ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/ata/Kconfig | 35 ++++++++++++++++++++++++++---------
 1 file changed, 26 insertions(+), 9 deletions(-)

diff --git a/drivers/ata/Kconfig b/drivers/ata/Kconfig
index a6beb2c5a692..dbde78feda31 100644
--- a/drivers/ata/Kconfig
+++ b/drivers/ata/Kconfig
@@ -92,22 +92,39 @@ config SATA_AHCI
 
 config SATA_MOBILE_LPM_POLICY
 	int "Default SATA Link Power Management policy for mobile chipsets"
-	range 0 4
+	range 0 5
 	default 0
 	depends on SATA_AHCI
 	help
 	  Select the Default SATA Link Power Management (LPM) policy to use
 	  for mobile / laptop variants of chipsets / "South Bridges".
 
-	  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 automatically
+		   transitions to partial and slumber).
+	   - DIPM: Device Initiated Power Management (device automatically
+		   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"
-- 
2.50.1