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[PATCH 3/3] ahci: Allow setting a default LPM policy for mobile chipsets




On many laptops setting a different LPM policy then unknown /
max_performance can lead to power-savings of 1.0 - 1.5 Watts (when idle).

Modern ultrabooks idle around 6W (at 50% screen brightness), 1.0 - 1.5W
is a significant chunk of this.

There are some performance / latency costs to enabling LPM by default,
so it is desirable to make it possible to set a different LPM policy
for mobile / laptop variants of chipsets / "South Bridges" vs their
desktop / server counterparts. Also enabling LPM by default is not
entirely without risk of regressions. At least min_power is known to
cause issues with some disks, including some reports of data corruption.

This commits adds a new ahci.mobile_lpm_policy kernel cmdline option,
which defaults to a new SATA_MOBILE_LPM_POLICY Kconfig option so that
Linux distributions can choose to set a LPM policy for mobile chipsets
by default.

The reason to have both a kernel cmdline option and a Kconfig default
value for it, is to allow easy overriding of the default to allow
trouble-shooting without needing to rebuild the kernel.

Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
---
 .config             |  1 +
 drivers/ata/Kconfig | 19 +++++++++++
 drivers/ata/ahci.c  | 97 +++++++++++++++++++++++++++++++----------------------
 drivers/ata/ahci.h  |  3 ++
 4 files changed, 79 insertions(+), 41 deletions(-)

diff --git a/.config b/.config
index 758cc273d9da..499dd1fe3cb8 100644
--- a/.config
+++ b/.config
@@ -2283,6 +2283,7 @@ CONFIG_SATA_PMP=y
 # Controllers with non-SFF native interface
 #
 CONFIG_SATA_AHCI=y
+CONFIG_SATA_MOBILE_LPM_POLICY=3
 CONFIG_SATA_AHCI_PLATFORM=m
 CONFIG_SATA_INIC162X=m
 CONFIG_SATA_ACARD_AHCI=m
diff --git a/drivers/ata/Kconfig b/drivers/ata/Kconfig
index cb5339166563..b3fad5663aeb 100644
--- a/drivers/ata/Kconfig
+++ b/drivers/ata/Kconfig
@@ -92,6 +92,25 @@ config SATA_AHCI
 
 	  If unsure, say N.
 
+config SATA_MOBILE_LPM_POLICY
+	int "Default SATA Link Power Management policy for mobile chipsets"
+	range 0 4
+	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:
+		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.
+
 config SATA_AHCI_PLATFORM
 	tristate "Platform AHCI SATA support"
 	help
diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 844f697bedbf..8e910fae8892 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -65,6 +65,7 @@ enum board_ids {
 	/* board IDs by feature in alphabetical order */
 	board_ahci,
 	board_ahci_ign_iferr,
+	board_ahci_mobile,
 	board_ahci_nomsi,
 	board_ahci_noncq,
 	board_ahci_nosntf,
@@ -140,6 +141,13 @@ static const struct ata_port_info ahci_port_info[] = {
 		.udma_mask	= ATA_UDMA6,
 		.port_ops	= &ahci_ops,
 	},
+	[board_ahci_mobile] = {
+		AHCI_HFLAGS	(AHCI_HFLAG_IS_MOBILE),
+		.flags		= AHCI_FLAG_COMMON,
+		.pio_mask	= ATA_PIO4,
+		.udma_mask	= ATA_UDMA6,
+		.port_ops	= &ahci_ops,
+	},
 	[board_ahci_nomsi] = {
 		AHCI_HFLAGS	(AHCI_HFLAG_NO_MSI),
 		.flags		= AHCI_FLAG_COMMON,
@@ -252,13 +260,13 @@ static const struct pci_device_id ahci_pci_tbl[] = {
 	{ PCI_VDEVICE(INTEL, 0x2924), board_ahci }, /* ICH9 */
 	{ PCI_VDEVICE(INTEL, 0x2925), board_ahci }, /* ICH9 */
 	{ PCI_VDEVICE(INTEL, 0x2927), board_ahci }, /* ICH9 */
-	{ PCI_VDEVICE(INTEL, 0x2929), board_ahci }, /* ICH9M */
-	{ PCI_VDEVICE(INTEL, 0x292a), board_ahci }, /* ICH9M */
-	{ PCI_VDEVICE(INTEL, 0x292b), board_ahci }, /* ICH9M */
-	{ PCI_VDEVICE(INTEL, 0x292c), board_ahci }, /* ICH9M */
-	{ PCI_VDEVICE(INTEL, 0x292f), board_ahci }, /* ICH9M */
+	{ PCI_VDEVICE(INTEL, 0x2929), board_ahci_mobile }, /* ICH9M */
+	{ PCI_VDEVICE(INTEL, 0x292a), board_ahci_mobile }, /* ICH9M */
+	{ PCI_VDEVICE(INTEL, 0x292b), board_ahci_mobile }, /* ICH9M */
+	{ PCI_VDEVICE(INTEL, 0x292c), board_ahci_mobile }, /* ICH9M */
+	{ PCI_VDEVICE(INTEL, 0x292f), board_ahci_mobile }, /* ICH9M */
 	{ PCI_VDEVICE(INTEL, 0x294d), board_ahci }, /* ICH9 */
-	{ PCI_VDEVICE(INTEL, 0x294e), board_ahci }, /* ICH9M */
+	{ PCI_VDEVICE(INTEL, 0x294e), board_ahci_mobile }, /* ICH9M */
 	{ PCI_VDEVICE(INTEL, 0x502a), board_ahci }, /* Tolapai */
 	{ PCI_VDEVICE(INTEL, 0x502b), board_ahci }, /* Tolapai */
 	{ PCI_VDEVICE(INTEL, 0x3a05), board_ahci }, /* ICH10 */
@@ -268,9 +276,9 @@ static const struct pci_device_id ahci_pci_tbl[] = {
 	{ PCI_VDEVICE(INTEL, 0x3b23), board_ahci }, /* PCH AHCI */
 	{ PCI_VDEVICE(INTEL, 0x3b24), board_ahci }, /* PCH RAID */
 	{ PCI_VDEVICE(INTEL, 0x3b25), board_ahci }, /* PCH RAID */
-	{ PCI_VDEVICE(INTEL, 0x3b29), board_ahci }, /* PCH M AHCI */
+	{ PCI_VDEVICE(INTEL, 0x3b29), board_ahci_mobile }, /* PCH M AHCI */
 	{ PCI_VDEVICE(INTEL, 0x3b2b), board_ahci }, /* PCH RAID */
-	{ PCI_VDEVICE(INTEL, 0x3b2c), board_ahci }, /* PCH M RAID */
+	{ PCI_VDEVICE(INTEL, 0x3b2c), board_ahci_mobile }, /* PCH M RAID */
 	{ PCI_VDEVICE(INTEL, 0x3b2f), board_ahci }, /* PCH AHCI */
 	{ PCI_VDEVICE(INTEL, 0x19b0), board_ahci }, /* DNV AHCI */
 	{ PCI_VDEVICE(INTEL, 0x19b1), board_ahci }, /* DNV AHCI */
@@ -293,9 +301,9 @@ static const struct pci_device_id ahci_pci_tbl[] = {
 	{ PCI_VDEVICE(INTEL, 0x19cE), board_ahci }, /* DNV AHCI */
 	{ PCI_VDEVICE(INTEL, 0x19cF), board_ahci }, /* DNV AHCI */
 	{ PCI_VDEVICE(INTEL, 0x1c02), board_ahci }, /* CPT AHCI */
-	{ PCI_VDEVICE(INTEL, 0x1c03), board_ahci }, /* CPT M AHCI */
+	{ PCI_VDEVICE(INTEL, 0x1c03), board_ahci_mobile }, /* CPT M AHCI */
 	{ PCI_VDEVICE(INTEL, 0x1c04), board_ahci }, /* CPT RAID */
-	{ PCI_VDEVICE(INTEL, 0x1c05), board_ahci }, /* CPT M RAID */
+	{ PCI_VDEVICE(INTEL, 0x1c05), board_ahci_mobile }, /* CPT M RAID */
 	{ PCI_VDEVICE(INTEL, 0x1c06), board_ahci }, /* CPT RAID */
 	{ PCI_VDEVICE(INTEL, 0x1c07), board_ahci }, /* CPT RAID */
 	{ PCI_VDEVICE(INTEL, 0x1d02), board_ahci }, /* PBG AHCI */
@@ -304,28 +312,28 @@ static const struct pci_device_id ahci_pci_tbl[] = {
 	{ PCI_VDEVICE(INTEL, 0x2826), board_ahci }, /* PBG RAID */
 	{ PCI_VDEVICE(INTEL, 0x2323), board_ahci }, /* DH89xxCC AHCI */
 	{ PCI_VDEVICE(INTEL, 0x1e02), board_ahci }, /* Panther Point AHCI */
-	{ PCI_VDEVICE(INTEL, 0x1e03), board_ahci }, /* Panther Point M AHCI */
+	{ PCI_VDEVICE(INTEL, 0x1e03), board_ahci_mobile }, /* Panther M AHCI */
 	{ PCI_VDEVICE(INTEL, 0x1e04), board_ahci }, /* Panther Point RAID */
 	{ PCI_VDEVICE(INTEL, 0x1e05), board_ahci }, /* Panther Point RAID */
 	{ PCI_VDEVICE(INTEL, 0x1e06), board_ahci }, /* Panther Point RAID */
-	{ PCI_VDEVICE(INTEL, 0x1e07), board_ahci }, /* Panther Point M RAID */
+	{ PCI_VDEVICE(INTEL, 0x1e07), board_ahci_mobile }, /* Panther M RAID */
 	{ PCI_VDEVICE(INTEL, 0x1e0e), board_ahci }, /* Panther Point RAID */
 	{ PCI_VDEVICE(INTEL, 0x8c02), board_ahci }, /* Lynx Point AHCI */
-	{ PCI_VDEVICE(INTEL, 0x8c03), board_ahci }, /* Lynx Point M AHCI */
+	{ PCI_VDEVICE(INTEL, 0x8c03), board_ahci_mobile }, /* Lynx M AHCI */
 	{ PCI_VDEVICE(INTEL, 0x8c04), board_ahci }, /* Lynx Point RAID */
-	{ PCI_VDEVICE(INTEL, 0x8c05), board_ahci }, /* Lynx Point M RAID */
+	{ PCI_VDEVICE(INTEL, 0x8c05), board_ahci_mobile }, /* Lynx M RAID */
 	{ PCI_VDEVICE(INTEL, 0x8c06), board_ahci }, /* Lynx Point RAID */
-	{ PCI_VDEVICE(INTEL, 0x8c07), board_ahci }, /* Lynx Point M RAID */
+	{ PCI_VDEVICE(INTEL, 0x8c07), board_ahci_mobile }, /* Lynx M RAID */
 	{ PCI_VDEVICE(INTEL, 0x8c0e), board_ahci }, /* Lynx Point RAID */
-	{ PCI_VDEVICE(INTEL, 0x8c0f), board_ahci }, /* Lynx Point M RAID */
-	{ PCI_VDEVICE(INTEL, 0x9c02), board_ahci }, /* Lynx Point-LP AHCI */
-	{ PCI_VDEVICE(INTEL, 0x9c03), board_ahci }, /* Lynx Point-LP AHCI */
-	{ PCI_VDEVICE(INTEL, 0x9c04), board_ahci }, /* Lynx Point-LP RAID */
-	{ PCI_VDEVICE(INTEL, 0x9c05), board_ahci }, /* Lynx Point-LP RAID */
-	{ PCI_VDEVICE(INTEL, 0x9c06), board_ahci }, /* Lynx Point-LP RAID */
-	{ PCI_VDEVICE(INTEL, 0x9c07), board_ahci }, /* Lynx Point-LP RAID */
-	{ PCI_VDEVICE(INTEL, 0x9c0e), board_ahci }, /* Lynx Point-LP RAID */
-	{ PCI_VDEVICE(INTEL, 0x9c0f), board_ahci }, /* Lynx Point-LP RAID */
+	{ PCI_VDEVICE(INTEL, 0x8c0f), board_ahci_mobile }, /* Lynx M RAID */
+	{ PCI_VDEVICE(INTEL, 0x9c02), board_ahci_mobile }, /* Lynx LP AHCI */
+	{ PCI_VDEVICE(INTEL, 0x9c03), board_ahci_mobile }, /* Lynx LP AHCI */
+	{ PCI_VDEVICE(INTEL, 0x9c04), board_ahci_mobile }, /* Lynx LP RAID */
+	{ PCI_VDEVICE(INTEL, 0x9c05), board_ahci_mobile }, /* Lynx LP RAID */
+	{ PCI_VDEVICE(INTEL, 0x9c06), board_ahci_mobile }, /* Lynx LP RAID */
+	{ PCI_VDEVICE(INTEL, 0x9c07), board_ahci_mobile }, /* Lynx LP RAID */
+	{ PCI_VDEVICE(INTEL, 0x9c0e), board_ahci_mobile }, /* Lynx LP RAID */
+	{ PCI_VDEVICE(INTEL, 0x9c0f), board_ahci_mobile }, /* Lynx LP RAID */
 	{ PCI_VDEVICE(INTEL, 0x1f22), board_ahci }, /* Avoton AHCI */
 	{ PCI_VDEVICE(INTEL, 0x1f23), board_ahci }, /* Avoton AHCI */
 	{ PCI_VDEVICE(INTEL, 0x1f24), board_ahci }, /* Avoton RAID */
@@ -353,26 +361,26 @@ static const struct pci_device_id ahci_pci_tbl[] = {
 	{ PCI_VDEVICE(INTEL, 0x8d66), board_ahci }, /* Wellsburg RAID */
 	{ PCI_VDEVICE(INTEL, 0x8d6e), board_ahci }, /* Wellsburg RAID */
 	{ PCI_VDEVICE(INTEL, 0x23a3), board_ahci }, /* Coleto Creek AHCI */
-	{ PCI_VDEVICE(INTEL, 0x9c83), board_ahci }, /* Wildcat Point-LP AHCI */
-	{ PCI_VDEVICE(INTEL, 0x9c85), board_ahci }, /* Wildcat Point-LP RAID */
-	{ PCI_VDEVICE(INTEL, 0x9c87), board_ahci }, /* Wildcat Point-LP RAID */
-	{ PCI_VDEVICE(INTEL, 0x9c8f), board_ahci }, /* Wildcat Point-LP RAID */
+	{ PCI_VDEVICE(INTEL, 0x9c83), board_ahci_mobile }, /* Wildcat LP AHCI */
+	{ PCI_VDEVICE(INTEL, 0x9c85), board_ahci_mobile }, /* Wildcat LP RAID */
+	{ PCI_VDEVICE(INTEL, 0x9c87), board_ahci_mobile }, /* Wildcat LP RAID */
+	{ PCI_VDEVICE(INTEL, 0x9c8f), board_ahci_mobile }, /* Wildcat LP RAID */
 	{ PCI_VDEVICE(INTEL, 0x8c82), board_ahci }, /* 9 Series AHCI */
-	{ PCI_VDEVICE(INTEL, 0x8c83), board_ahci }, /* 9 Series M AHCI */
+	{ PCI_VDEVICE(INTEL, 0x8c83), board_ahci_mobile }, /* 9 Series M AHCI */
 	{ PCI_VDEVICE(INTEL, 0x8c84), board_ahci }, /* 9 Series RAID */
-	{ PCI_VDEVICE(INTEL, 0x8c85), board_ahci }, /* 9 Series M RAID */
+	{ PCI_VDEVICE(INTEL, 0x8c85), board_ahci_mobile }, /* 9 Series M RAID */
 	{ PCI_VDEVICE(INTEL, 0x8c86), board_ahci }, /* 9 Series RAID */
-	{ PCI_VDEVICE(INTEL, 0x8c87), board_ahci }, /* 9 Series M RAID */
+	{ PCI_VDEVICE(INTEL, 0x8c87), board_ahci_mobile }, /* 9 Series M RAID */
 	{ PCI_VDEVICE(INTEL, 0x8c8e), board_ahci }, /* 9 Series RAID */
-	{ PCI_VDEVICE(INTEL, 0x8c8f), board_ahci }, /* 9 Series M RAID */
-	{ PCI_VDEVICE(INTEL, 0x9d03), board_ahci }, /* Sunrise Point-LP AHCI */
-	{ PCI_VDEVICE(INTEL, 0x9d05), board_ahci }, /* Sunrise Point-LP RAID */
-	{ PCI_VDEVICE(INTEL, 0x9d07), board_ahci }, /* Sunrise Point-LP RAID */
+	{ PCI_VDEVICE(INTEL, 0x8c8f), board_ahci_mobile }, /* 9 Series M RAID */
+	{ PCI_VDEVICE(INTEL, 0x9d03), board_ahci_mobile }, /* Sunrise LP AHCI */
+	{ PCI_VDEVICE(INTEL, 0x9d05), board_ahci_mobile }, /* Sunrise LP RAID */
+	{ PCI_VDEVICE(INTEL, 0x9d07), board_ahci_mobile }, /* Sunrise LP RAID */
 	{ PCI_VDEVICE(INTEL, 0xa102), board_ahci }, /* Sunrise Point-H AHCI */
-	{ PCI_VDEVICE(INTEL, 0xa103), board_ahci }, /* Sunrise Point-H M AHCI */
+	{ PCI_VDEVICE(INTEL, 0xa103), board_ahci_mobile }, /* Sunrise M AHCI */
 	{ PCI_VDEVICE(INTEL, 0xa105), board_ahci }, /* Sunrise Point-H RAID */
 	{ PCI_VDEVICE(INTEL, 0xa106), board_ahci }, /* Sunrise Point-H RAID */
-	{ PCI_VDEVICE(INTEL, 0xa107), board_ahci }, /* Sunrise Point-H M RAID */
+	{ PCI_VDEVICE(INTEL, 0xa107), board_ahci_mobile }, /* Sunrise M RAID */
 	{ PCI_VDEVICE(INTEL, 0xa10f), board_ahci }, /* Sunrise Point-H RAID */
 	{ PCI_VDEVICE(INTEL, 0x2822), board_ahci }, /* Lewisburg RAID*/
 	{ PCI_VDEVICE(INTEL, 0x2823), board_ahci }, /* Lewisburg AHCI*/
@@ -386,10 +394,10 @@ static const struct pci_device_id ahci_pci_tbl[] = {
 	{ PCI_VDEVICE(INTEL, 0xa206), board_ahci }, /* Lewisburg RAID*/
 	{ PCI_VDEVICE(INTEL, 0xa252), board_ahci }, /* Lewisburg RAID*/
 	{ PCI_VDEVICE(INTEL, 0xa256), board_ahci }, /* Lewisburg RAID*/
-	{ PCI_VDEVICE(INTEL, 0x0f22), board_ahci }, /* Bay Trail AHCI */
-	{ PCI_VDEVICE(INTEL, 0x0f23), board_ahci }, /* Bay Trail AHCI */
-	{ PCI_VDEVICE(INTEL, 0x22a3), board_ahci }, /* Cherry Trail AHCI */
-	{ PCI_VDEVICE(INTEL, 0x5ae3), board_ahci }, /* Apollo Lake AHCI */
+	{ PCI_VDEVICE(INTEL, 0x0f22), board_ahci_mobile }, /* Bay Trail AHCI */
+	{ PCI_VDEVICE(INTEL, 0x0f23), board_ahci_mobile }, /* Bay Trail AHCI */
+	{ PCI_VDEVICE(INTEL, 0x22a3), board_ahci_mobile }, /* Cherry Tr. AHCI */
+	{ PCI_VDEVICE(INTEL, 0x5ae3), board_ahci_mobile }, /* ApolloLake AHCI */
 
 	/* JMicron 360/1/3/5/6, match class to avoid IDE function */
 	{ PCI_VENDOR_ID_JMICRON, PCI_ANY_ID, PCI_ANY_ID, PCI_ANY_ID,
@@ -597,6 +605,9 @@ static int marvell_enable = 1;
 module_param(marvell_enable, int, 0644);
 MODULE_PARM_DESC(marvell_enable, "Marvell SATA via AHCI (1 = enabled)");
 
+static int mobile_lpm_policy = CONFIG_SATA_MOBILE_LPM_POLICY;
+module_param(mobile_lpm_policy, int, 0644);
+MODULE_PARM_DESC(mobile_lpm_policy, "Default LPM policy for mobile chipsets");
 
 static void ahci_pci_save_initial_config(struct pci_dev *pdev,
 					 struct ahci_host_priv *hpriv)
@@ -1732,6 +1743,10 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 		if (ap->flags & ATA_FLAG_EM)
 			ap->em_message_type = hpriv->em_msg_type;
 
+		if ((hpriv->flags & AHCI_HFLAG_IS_MOBILE) &&
+		    mobile_lpm_policy >= ATA_LPM_UNKNOWN &&
+		    mobile_lpm_policy <= ATA_LPM_MIN_POWER)
+			ap->target_lpm_policy = mobile_lpm_policy;
 
 		/* disabled/not-implemented port */
 		if (!(hpriv->port_map & (1 << i)))
diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
index 749fd94441b0..a9d996e17d75 100644
--- a/drivers/ata/ahci.h
+++ b/drivers/ata/ahci.h
@@ -251,6 +251,9 @@ enum {
 	AHCI_HFLAG_YES_ALPM		= (1 << 23), /* force ALPM cap on */
 	AHCI_HFLAG_NO_WRITE_TO_RO	= (1 << 24), /* don't write to read
 							only registers */
+	AHCI_HFLAG_IS_MOBILE		= (1 << 25), /* mobile chipset, use
+							SATA_MOBILE_LPM_POLICY
+							as default lpm_policy */
 
 	/* ap->flags bits */
 
-- 
2.14.3