libata: reimplement link power management

The current LPM implementation has the following issues.

* Operation order isn't well thought-out.  e.g. HIPM should be
  configured after IPM in SControl is properly configured.  Not the
  other way around.

* Suspend/resume paths call ata_lpm_enable/disable() which must only
  be called from EH context directly.  Also, ata_lpm_enable/disable()
  were called whether LPM was in use or not.

* Implementation is per-port when it should be per-link.  As a result,
  it can't be used for controllers with slave links or PMP.

* LPM state isn't managed consistently.  After a link reset for
  whatever reason including suspend/resume the actual LPM state would
  be reset leaving ap->lpm_policy inconsistent.

* Generic/driver-specific logic boundary isn't clear.  Currently,
  libahci has to mangle stuff which libata EH proper should be
  handling.  This makes the implementation unnecessarily complex and
  fragile.

* Tied to ALPM.  Doesn't consider DIPM only cases and doesn't check
  whether the device allows HIPM.

* Error handling isn't implemented.

Given the extent of mismatch with the rest of libata, I don't think
trying to fix it piecewise makes much sense.  This patch reimplements
LPM support.

* The new implementation is per-link.  The target policy is still
  port-wide (ap->target_lpm_policy) but all the mechanisms and states
  are per-link and integrate well with the rest of link abstraction
  and can work with slave and PMP links.

* Core EH has proper control of LPM state.  LPM state is reconfigured
  when and only when reconfiguration is necessary.  It makes sure that
  LPM state is reset when probing for new device on the link.
  Controller agnostic logic is now implemented in libata EH proper and
  driver implementation only has to deal with controller specifics.

* Proper error handling.  LPM config failure is attributed to the
  device on the link and LPM is disabled for the link if it fails
  repeatedly.

* ops->enable/disable_pm() are replaced with single ops->set_lpm()
  which takes @policy and @hints.  This simplifies driver specific
  implementation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

1 files changed, 1 insertions, 200 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index b8024451234c..7c5538b9fa3b 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -1028,182 +1028,6 @@ const char *sata_spd_string(unsigned int spd)
 	return spd_str[spd - 1];
 }
 
-static int ata_dev_set_dipm(struct ata_device *dev, enum ata_lpm_policy policy)
-{
-	struct ata_link *link = dev->link;
-	struct ata_port *ap = link->ap;
-	u32 scontrol;
-	unsigned int err_mask;
-	int rc;
-
-	/*
-	 * disallow DIPM for drivers which haven't set
-	 * ATA_FLAG_LPM.  This is because when DIPM is enabled,
-	 * phy ready will be set in the interrupt status on
-	 * state changes, which will cause some drivers to
-	 * think there are errors - additionally drivers will
-	 * need to disable hot plug.
-	 */
-	if (!(ap->flags & ATA_FLAG_LPM) || !ata_dev_enabled(dev)) {
-		ap->lpm_policy = ATA_LPM_UNKNOWN;
-		return -EINVAL;
-	}
-
-	/*
-	 * For DIPM, we will only enable it for the
-	 * min_power setting.
-	 *
-	 * Why?  Because Disks are too stupid to know that
-	 * If the host rejects a request to go to SLUMBER
-	 * they should retry at PARTIAL, and instead it
-	 * just would give up.  So, for medium_power to
-	 * work at all, we need to only allow HIPM.
-	 */
-	rc = sata_scr_read(link, SCR_CONTROL, &scontrol);
-	if (rc)
-		return rc;
-
-	switch (policy) {
-	case ATA_LPM_MIN_POWER:
-		/* no restrictions on LPM transitions */
-		scontrol &= ~(0x3 << 8);
-		rc = sata_scr_write(link, SCR_CONTROL, scontrol);
-		if (rc)
-			return rc;
-
-		/* enable DIPM */
-		if (dev->flags & ATA_DFLAG_DIPM)
-			err_mask = ata_dev_set_feature(dev,
-					SETFEATURES_SATA_ENABLE, SATA_DIPM);
-		break;
-	case ATA_LPM_MED_POWER:
-		/* allow LPM to PARTIAL */
-		scontrol &= ~(0x1 << 8);
-		scontrol |= (0x2 << 8);
-		rc = sata_scr_write(link, SCR_CONTROL, scontrol);
-		if (rc)
-			return rc;
-
-		/*
-		 * we don't have to disable DIPM since LPM flags
-		 * disallow transitions to SLUMBER, which effectively
-		 * disable DIPM if it does not support PARTIAL
-		 */
-		break;
-	case ATA_LPM_UNKNOWN:
-	case ATA_LPM_MAX_POWER:
-		/* disable all LPM transitions */
-		scontrol |= (0x3 << 8);
-		rc = sata_scr_write(link, SCR_CONTROL, scontrol);
-		if (rc)
-			return rc;
-
-		/*
-		 * we don't have to disable DIPM since LPM flags
-		 * disallow all transitions which effectively
-		 * disable DIPM anyway.
-		 */
-		break;
-	}
-
-	/* FIXME: handle SET FEATURES failure */
-	(void) err_mask;
-
-	return 0;
-}
-
-/**
- *	ata_dev_enable_pm - enable SATA interface power management
- *	@dev:  device to enable power management
- *	@policy: the link power management policy
- *
- *	Enable SATA Interface power management.  This will enable
- *	Device Interface Power Management (DIPM) for min_power
- * 	policy, and then call driver specific callbacks for
- *	enabling Host Initiated Power management.
- *
- *	Locking: Caller.
- *	Returns: -EINVAL if LPM is not supported, 0 otherwise.
- */
-void ata_dev_enable_pm(struct ata_device *dev, enum ata_lpm_policy policy)
-{
-	int rc = 0;
-	struct ata_port *ap = dev->link->ap;
-
-	/* set HIPM first, then DIPM */
-	if (ap->ops->enable_pm)
-		rc = ap->ops->enable_pm(ap, policy);
-	if (rc)
-		goto enable_pm_out;
-	rc = ata_dev_set_dipm(dev, policy);
-
-enable_pm_out:
-	if (rc)
-		ap->lpm_policy = ATA_LPM_MAX_POWER;
-	else
-		ap->lpm_policy = policy;
-	return /* rc */;	/* hopefully we can use 'rc' eventually */
-}
-
-#ifdef CONFIG_PM
-/**
- *	ata_dev_disable_pm - disable SATA interface power management
- *	@dev: device to disable power management
- *
- *	Disable SATA Interface power management.  This will disable
- *	Device Interface Power Management (DIPM) without changing
- * 	policy,  call driver specific callbacks for disabling Host
- * 	Initiated Power management.
- *
- *	Locking: Caller.
- *	Returns: void
- */
-static void ata_dev_disable_pm(struct ata_device *dev)
-{
-	struct ata_port *ap = dev->link->ap;
-
-	ata_dev_set_dipm(dev, ATA_LPM_MAX_POWER);
-	if (ap->ops->disable_pm)
-		ap->ops->disable_pm(ap);
-}
-#endif	/* CONFIG_PM */
-
-void ata_lpm_schedule(struct ata_port *ap, enum ata_lpm_policy policy)
-{
-	ap->lpm_policy = policy;
-	ap->link.eh_info.action |= ATA_EH_LPM;
-	ap->link.eh_info.flags |= ATA_EHI_NO_AUTOPSY;
-	ata_port_schedule_eh(ap);
-}
-
-#ifdef CONFIG_PM
-static void ata_lpm_enable(struct ata_host *host)
-{
-	struct ata_link *link;
-	struct ata_port *ap;
-	struct ata_device *dev;
-	int i;
-
-	for (i = 0; i < host->n_ports; i++) {
-		ap = host->ports[i];
-		ata_for_each_link(link, ap, EDGE) {
-			ata_for_each_dev(dev, link, ALL)
-				ata_dev_disable_pm(dev);
-		}
-	}
-}
-
-static void ata_lpm_disable(struct ata_host *host)
-{
-	int i;
-
-	for (i = 0; i < host->n_ports; i++) {
-		struct ata_port *ap = host->ports[i];
-		ata_lpm_schedule(ap, ap->lpm_policy);
-	}
-}
-#endif	/* CONFIG_PM */
-
 /**
  *	ata_dev_classify - determine device type based on ATA-spec signature
  *	@tf: ATA taskfile register set for device to be identified
@@ -2562,13 +2386,6 @@ int ata_dev_configure(struct ata_device *dev)
 	if (dev->flags & ATA_DFLAG_LBA48)
 		dev->max_sectors = ATA_MAX_SECTORS_LBA48;
 
-	if (!(dev->horkage & ATA_HORKAGE_LPM)) {
-		if (ata_id_has_hipm(dev->id))
-			dev->flags |= ATA_DFLAG_HIPM;
-		if (ata_id_has_dipm(dev->id))
-			dev->flags |= ATA_DFLAG_DIPM;
-	}
-
 	/* Limit PATA drive on SATA cable bridge transfers to udma5,
 	   200 sectors */
 	if (ata_dev_knobble(dev)) {
@@ -2589,13 +2406,6 @@ int ata_dev_configure(struct ata_device *dev)
 		dev->max_sectors = min_t(unsigned int, ATA_MAX_SECTORS_128,
 					 dev->max_sectors);
 
-	if (ata_dev_blacklisted(dev) & ATA_HORKAGE_LPM) {
-		dev->horkage |= ATA_HORKAGE_LPM;
-
-		/* reset link pm_policy for this port to no pm */
-		ap->lpm_policy = ATA_LPM_MAX_POWER;
-	}
-
 	if (ap->ops->dev_config)
 		ap->ops->dev_config(dev);
 
@@ -5495,12 +5305,6 @@ int ata_host_suspend(struct ata_host *host, pm_message_t mesg)
 	int rc;
 
 	/*
-	 * disable link pm on all ports before requesting
-	 * any pm activity
-	 */
-	ata_lpm_enable(host);
-
-	/*
 	 * On some hardware, device fails to respond after spun down
 	 * for suspend.  As the device won't be used before being
 	 * resumed, we don't need to touch the device.  Ask EH to skip
@@ -5533,9 +5337,6 @@ void ata_host_resume(struct ata_host *host)
 	ata_host_request_pm(host, PMSG_ON, ATA_EH_RESET,
 			    ATA_EHI_NO_AUTOPSY | ATA_EHI_QUIET, 0);
 	host->dev->power.power_state = PMSG_ON;
-
-	/* reenable link pm */
-	ata_lpm_disable(host);
 }
 #endif
 
@@ -6096,7 +5897,7 @@ static void async_port_probe(void *data, async_cookie_t cookie)
 		spin_lock_irqsave(ap->lock, flags);
 
 		ehi->probe_mask |= ATA_ALL_DEVICES;
-		ehi->action |= ATA_EH_RESET | ATA_EH_LPM;
+		ehi->action |= ATA_EH_RESET;
 		ehi->flags |= ATA_EHI_NO_AUTOPSY | ATA_EHI_QUIET;
 
 		ap->pflags &= ~ATA_PFLAG_INITIALIZING;