Re: [patch 2/2] Enable Aggressive Link Power management for AHCIcontrollers.

From: Jeff Garzik
Date: Thu Oct 25 2007 - 01:35:02 EST

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Kristen Carlson Accardi wrote:

This patch will set the correct bits to turn on Aggressive
Link Power Management (ALPM) for the ahci driver. This
will cause the controller and disk to negotiate a lower
power state for the link when there is no activity (see
the AHCI 1.x spec for details). This feature is mutually
exclusive with Hot Plug, so when ALPM is enabled, Hot Plug
is disabled. ALPM will be enabled by default, but it is
settable via the scsi host syfs interface. Possible settings for this feature are:

Setting Effect
----------------------------------------------------------
min_power ALPM is enabled, and link set to enter lowest power state (SLUMBER) when idle
Hot plug not allowed.

max_performance ALPM is disabled, Hot Plug is allowed

medium_power ALPM is enabled, and link set to enter
second lowest power state (PARTIAL) when
idle. Hot plug not allowed.

Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@xxxxxxxxx>

applied, with minor changes (attached)

Please check libata-dev.git#alpm and make sure it still works as expected (after it mirrors out to git.kernel.org)

commit 0fdf9763a76f4cce208b7139e555019217765e81
Author: Kristen Carlson Accardi <kristen.c.accardi@xxxxxxxxx>
Date: Thu Oct 25 01:33:26 2007 -0400

[libata] AHCI: add hw link power management support

This patch will set the correct bits to turn on Aggressive
Link Power Management (ALPM) for the ahci driver. This
will cause the controller and disk to negotiate a lower
power state for the link when there is no activity (see
the AHCI 1.x spec for details). This feature is mutually
exclusive with Hot Plug, so when ALPM is enabled, Hot Plug
is disabled. ALPM will be enabled by default, but it is
settable via the scsi host syfs interface. Possible
settings for this feature are:

Setting Effect
----------------------------------------------------------
min_power ALPM is enabled, and link set to enter
lowest power state (SLUMBER) when idle
Hot plug not allowed.

max_performance ALPM is disabled, Hot Plug is allowed

medium_power ALPM is enabled, and link set to enter
second lowest power state (PARTIAL) when
idle. Hot plug not allowed.

Signed-off-by: Kristen Carlson Accardi <kristen.c.accardi@xxxxxxxxx>
Signed-off-by: Jeff Garzik <jgarzik@xxxxxxxxxx>

drivers/ata/ahci.c | 157 ++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 155 insertions(+), 2 deletions(-)

0fdf9763a76f4cce208b7139e555019217765e81
diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c
index 95229e7..2b4faca 100644
--- a/drivers/ata/ahci.c
+++ b/drivers/ata/ahci.c
@@ -48,6 +48,9 @@
#define DRV_NAME "ahci"
#define DRV_VERSION "3.0"

+static int ahci_enable_alpm(struct ata_port *ap,
+ enum link_pm policy);
+static void ahci_disable_alpm(struct ata_port *ap);

enum {
AHCI_PCI_BAR = 5,
@@ -98,6 +101,7 @@ enum {
HOST_CAP_SSC = (1 << 14), /* Slumber capable */
HOST_CAP_PMP = (1 << 17), /* Port Multiplier support */
HOST_CAP_CLO = (1 << 24), /* Command List Override support */
+ HOST_CAP_ALPM = (1 << 26), /* Aggressive Link PM support */
HOST_CAP_SSS = (1 << 27), /* Staggered Spin-up */
HOST_CAP_SNTF = (1 << 29), /* SNotification register */
HOST_CAP_NCQ = (1 << 30), /* Native Command Queueing */
@@ -154,6 +158,8 @@ enum {
PORT_IRQ_PIOS_FIS | PORT_IRQ_D2H_REG_FIS,

/* PORT_CMD bits */
+ PORT_CMD_ASP = (1 << 27), /* Aggressive Slumber/Partial */
+ PORT_CMD_ALPE = (1 << 26), /* Aggressive Link PM enable */
PORT_CMD_ATAPI = (1 << 24), /* Device is ATAPI */
PORT_CMD_PMP = (1 << 17), /* PMP attached */
PORT_CMD_LIST_ON = (1 << 15), /* cmd list DMA engine running */
@@ -177,13 +183,14 @@ enum {
AHCI_HFLAG_MV_PATA = (1 << 4), /* PATA port */
AHCI_HFLAG_NO_MSI = (1 << 5), /* no PCI MSI */
AHCI_HFLAG_NO_PMP = (1 << 6), /* no PMP */
+ AHCI_HFLAG_NO_HOTPLUG = (1 << 7), /* ignore PxSERR.DIAG.N */

/* ap->flags bits */
- AHCI_FLAG_NO_HOTPLUG = (1 << 24), /* ignore PxSERR.DIAG.N */

AHCI_FLAG_COMMON = ATA_FLAG_SATA | ATA_FLAG_NO_LEGACY |
ATA_FLAG_MMIO | ATA_FLAG_PIO_DMA |
- ATA_FLAG_ACPI_SATA | ATA_FLAG_AN,
+ ATA_FLAG_ACPI_SATA | ATA_FLAG_AN |
+ ATA_FLAG_IPM,
AHCI_LFLAG_COMMON = ATA_LFLAG_SKIP_D2H_BSY,
};

@@ -252,6 +259,11 @@ static int ahci_pci_device_suspend(struct pci_dev *pdev, pm_message_t mesg);
static int ahci_pci_device_resume(struct pci_dev *pdev);
#endif

+static struct class_device_attribute *ahci_shost_attrs[] = {
+ &class_device_attr_link_power_management_policy,
+ NULL
+};
+
static struct scsi_host_template ahci_sht = {
.module = THIS_MODULE,
.name = DRV_NAME,
@@ -269,6 +281,7 @@ static struct scsi_host_template ahci_sht = {
.slave_configure = ata_scsi_slave_config,
.slave_destroy = ata_scsi_slave_destroy,
.bios_param = ata_std_bios_param,
+ .shost_attrs = ahci_shost_attrs,
};

static const struct ata_port_operations ahci_ops = {
@@ -300,6 +313,8 @@ static const struct ata_port_operations ahci_ops = {
.port_suspend = ahci_port_suspend,
.port_resume = ahci_port_resume,
#endif
+ .enable_pm = ahci_enable_alpm,
+ .disable_pm = ahci_disable_alpm,

.port_start = ahci_port_start,
.port_stop = ahci_port_stop,
@@ -800,6 +815,130 @@ static void ahci_power_up(struct ata_port *ap)
writel(cmd | PORT_CMD_ICC_ACTIVE, port_mmio + PORT_CMD);
}

+static void ahci_disable_alpm(struct ata_port *ap)
+{
+ struct ahci_host_priv *hpriv = ap->host->private_data;
+ void __iomem *port_mmio = ahci_port_base(ap);
+ u32 cmd;
+ struct ahci_port_priv *pp = ap->private_data;
+
+ /* IPM bits should be disabled by libata-core */
+ /* get the existing command bits */
+ cmd = readl(port_mmio + PORT_CMD);
+
+ /* disable ALPM and ASP */
+ cmd &= ~PORT_CMD_ASP;
+ cmd &= ~PORT_CMD_ALPE;
+
+ /* force the interface back to active */
+ cmd |= PORT_CMD_ICC_ACTIVE;
+
+ /* write out new cmd value */
+ writel(cmd, port_mmio + PORT_CMD);
+ cmd = readl(port_mmio + PORT_CMD);
+
+ /* wait 10ms to be sure we've come out of any low power state */
+ msleep(10);
+
+ /* clear out any PhyRdy stuff from interrupt status */
+ writel(PORT_IRQ_PHYRDY, port_mmio + PORT_IRQ_STAT);
+
+ /* go ahead and clean out PhyRdy Change from Serror too */
+ ahci_scr_write(ap, SCR_ERROR, ((1 << 16) | (1 << 18)));
+
+ /*
+ * Clear flag to indicate that we should ignore all PhyRdy
+ * state changes
+ */
+ hpriv->flags &= ~AHCI_HFLAG_NO_HOTPLUG;
+
+ /*
+ * Enable interrupts on Phy Ready.
+ */
+ pp->intr_mask |= PORT_IRQ_PHYRDY;
+ writel(pp->intr_mask, port_mmio + PORT_IRQ_MASK);
+
+ /*
+ * don't change the link pm policy - we can be called
+ * just to turn of link pm temporarily
+ */
+}
+
+static int ahci_enable_alpm(struct ata_port *ap,
+ enum link_pm policy)
+{
+ struct ahci_host_priv *hpriv = ap->host->private_data;
+ void __iomem *port_mmio = ahci_port_base(ap);
+ u32 cmd;
+ struct ahci_port_priv *pp = ap->private_data;
+ u32 asp;
+
+ /* Make sure the host is capable of link power management */
+ if (!(hpriv->cap & HOST_CAP_ALPM))
+ return -EINVAL;
+
+ switch (policy) {
+ case MAX_PERFORMANCE:
+ case NOT_AVAILABLE:
+ /*
+ * if we came here with NOT_AVAILABLE,
+ * it just means this is the first time we
+ * have tried to enable - default to max performance,
+ * and let the user go to lower power modes on request.
+ */
+ ahci_disable_alpm(ap);
+ return 0;
+ case MIN_POWER:
+ /* configure HBA to enter SLUMBER */
+ asp = PORT_CMD_ASP;
+ break;
+ case MEDIUM_POWER:
+ /* configure HBA to enter PARTIAL */
+ asp = 0;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ /*
+ * Disable interrupts on Phy Ready. This keeps us from
+ * getting woken up due to spurious phy ready interrupts
+ * TBD - Hot plug should be done via polling now, is
+ * that even supported?
+ */
+ pp->intr_mask &= ~PORT_IRQ_PHYRDY;
+ writel(pp->intr_mask, port_mmio + PORT_IRQ_MASK);
+
+ /*
+ * Set a flag to indicate that we should ignore all PhyRdy
+ * state changes since these can happen now whenever we
+ * change link state
+ */
+ hpriv->flags |= AHCI_HFLAG_NO_HOTPLUG;
+
+ /* get the existing command bits */
+ cmd = readl(port_mmio + PORT_CMD);
+
+ /*
+ * Set ASP based on Policy
+ */
+ cmd |= asp;
+
+ /*
+ * Setting this bit will instruct the HBA to aggressively
+ * enter a lower power link state when it's appropriate and
+ * based on the value set above for ASP
+ */
+ cmd |= PORT_CMD_ALPE;
+
+ /* write out new cmd value */
+ writel(cmd, port_mmio + PORT_CMD);
+ cmd = readl(port_mmio + PORT_CMD);
+
+ /* IPM bits should be set by libata-core */
+ return 0;
+}
+
#ifdef CONFIG_PM
static void ahci_power_down(struct ata_port *ap)
{
@@ -1426,6 +1565,17 @@ static void ahci_port_intr(struct ata_port *ap)
if (unlikely(resetting))
status &= ~PORT_IRQ_BAD_PMP;

+ /* If we are getting PhyRdy, this is
+ * just a power state change, we should
+ * clear out this, plus the PhyRdy/Comm
+ * Wake bits from Serror
+ */
+ if ((hpriv->flags & AHCI_HFLAG_NO_HOTPLUG) &&
+ (status & PORT_IRQ_PHYRDY)) {
+ status &= ~PORT_IRQ_PHYRDY;
+ ahci_scr_write(ap, SCR_ERROR, ((1 << 16) | (1 << 18)));
+ }
+
if (unlikely(status & PORT_IRQ_ERROR)) {
ahci_error_intr(ap, status);
return;
@@ -2015,6 +2165,9 @@ static int ahci_init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
ata_port_pbar_desc(ap, AHCI_PCI_BAR,
0x100 + ap->port_no * 0x80, "port");

+ /* set initial link pm policy */
+ ap->pm_policy = NOT_AVAILABLE;
+
/* standard SATA port setup */
if (hpriv->port_map & (1 << i))
ap->ioaddr.cmd_addr = port_mmio;

Next message: Pekka Enberg: "Re: [PATCH+comment] fix tmpfs BUG and AOP_WRITEPAGE_ACTIVATE"
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