Re: [PATCH] sh_tmu / PM: Prevent power from being removed from TMU devices

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Tuesday, March 06, 2012, Paul Mundt wrote:
> On Mon, Mar 05, 2012 at 11:46:08PM +0100, Rafael J. Wysocki wrote:
> > On Monday, March 05, 2012, Rafael J. Wysocki wrote:
> > > Anyway, to use the same approach in all three drivers we need a flag that
> > > will allow a driver to say "don't power down the domain this device belongs to"
> > > to the core.  It shouldn't be very difficult to introduce it, but I'm still
> > > not sure that will make the "TMU vs system resume" problem mentioned above go
> > > away.
> > > 
> > > I'll try to prepare a patch for that later today anyway.
> > 
> > Is appended.  Without a changelog for now, because I need to add CMT and
> > MTU2 to it still.
> > 
> The updated version looks much nicer, and the interaction with early
> platform entry is quite obvious. If we can reuse this for CMT and MTU2
> then that should about take care of it.

I believe that we can.

> Thanks for persisting!

No problem.

Below is a full patch with a changelog and CMT and MTU2 changes too.
This has been tested on Mackerel both with and without the TMU driver
without causing any visible issues to appear.

Thanks,
Rafael

---
From: Rafael J. Wysocki <rjw@sisk.pl>
Subject: PM / shmobile: Mark clocksource devices as "always on"

The TMU device on the Mackerel board belongs to the A4R power domain
and loses power when the domain is turned off.  Unfortunately, the
TMU driver is not prepared to cope with such situations and crashes
the system when that happens.  To work around this problem introduce
a new helper function, pm_genpd_dev_always_on(), allowing a device
driver to mark its device as "always on" in case it belongs to a PM
domain, which will make the generic PM domains core code avoid
powering off the domain containing the device, both at run time and
during system suspend.

Make the TMU driver use pm_genpd_dev_always_on() to prevent the
A4R domain from losing power and make the other SH colocksource
drivers, sh_cmt and sh_mtu2, behave analogously.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
 arch/arm/mach-shmobile/setup-sh7372.c |    2 ++
 drivers/base/power/domain.c           |   28 ++++++++++++++++++++++++++--
 drivers/clocksource/sh_cmt.c          |    4 ++++
 drivers/clocksource/sh_mtu2.c         |    4 ++++
 drivers/clocksource/sh_tmu.c          |    4 ++++
 include/linux/pm_domain.h             |    3 +++
 6 files changed, 43 insertions(+), 2 deletions(-)

Index: linux/drivers/base/power/domain.c
=================================--- linux.orig/drivers/base/power/domain.c
+++ linux/drivers/base/power/domain.c
@@ -372,7 +372,7 @@ static int pm_genpd_poweroff(struct gene
 	not_suspended = 0;
 	list_for_each_entry(pdd, &genpd->dev_list, list_node)
 		if (pdd->dev->driver && (!pm_runtime_suspended(pdd->dev)
-		    || pdd->dev->power.irq_safe))
+		    || pdd->dev->power.irq_safe || to_gpd_data(pdd)->always_on))
 			not_suspended++;
 
 	if (not_suspended > genpd->in_progress)
@@ -509,6 +509,9 @@ static int pm_genpd_runtime_suspend(stru
 
 	might_sleep_if(!genpd->dev_irq_safe);
 
+	if (dev_gpd_data(dev)->always_on)
+		return -EBUSY;
+
 	stop_ok = genpd->gov ? genpd->gov->stop_ok : NULL;
 	if (stop_ok && !stop_ok(dev))
 		return -EBUSY;
@@ -864,7 +867,8 @@ static int pm_genpd_suspend_noirq(struct
 		return -EINVAL;
 
 	if (genpd->suspend_power_off
-	    || (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev)))
+	    || (dev->power.wakeup_path && genpd_dev_active_wakeup(genpd, dev))
+	    || dev_gpd_data(dev)->always_on)
 		return 0;
 
 	genpd_stop_dev(genpd, dev);
@@ -1281,6 +1285,26 @@ int pm_genpd_remove_device(struct generi
 }
 
 /**
+ * pm_genpd_dev_always_on - Set/unset the "always on" flag for a given device.
+ * @dev: Device to set/unset the flag for.
+ * @val: The new value of the device's "always on" flag.
+ */
+void pm_genpd_dev_always_on(struct device *dev, bool val)
+{
+	struct pm_subsys_data *psd;
+	unsigned long flags;
+
+	spin_lock_irqsave(&dev->power.lock, flags);
+
+	psd = dev_to_psd(dev);
+	if (psd && psd->domain_data)
+		to_gpd_data(psd->domain_data)->always_on = val;
+
+	spin_unlock_irqrestore(&dev->power.lock, flags);
+}
+EXPORT_SYMBOL_GPL(pm_genpd_dev_always_on);
+
+/**
  * pm_genpd_add_subdomain - Add a subdomain to an I/O PM domain.
  * @genpd: Master PM domain to add the subdomain to.
  * @subdomain: Subdomain to be added.
Index: linux/include/linux/pm_domain.h
=================================--- linux.orig/include/linux/pm_domain.h
+++ linux/include/linux/pm_domain.h
@@ -97,6 +97,7 @@ struct generic_pm_domain_data {
 	struct gpd_dev_ops ops;
 	struct gpd_timing_data td;
 	bool need_restore;
+	bool always_on;
 };
 
 #ifdef CONFIG_PM_GENERIC_DOMAINS
@@ -125,6 +126,7 @@ static inline int pm_genpd_add_device(st
 
 extern int pm_genpd_remove_device(struct generic_pm_domain *genpd,
 				  struct device *dev);
+extern void pm_genpd_dev_always_on(struct device *dev, bool val);
 extern int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
 				  struct generic_pm_domain *new_subdomain);
 extern int pm_genpd_remove_subdomain(struct generic_pm_domain *genpd,
@@ -167,6 +169,7 @@ static inline int pm_genpd_remove_device
 {
 	return -ENOSYS;
 }
+static inline void pm_genpd_dev_always_on(struct device *dev, bool val) {}
 static inline int pm_genpd_add_subdomain(struct generic_pm_domain *genpd,
 					 struct generic_pm_domain *new_sd)
 {
Index: linux/drivers/clocksource/sh_tmu.c
=================================--- linux.orig/drivers/clocksource/sh_tmu.c
+++ linux/drivers/clocksource/sh_tmu.c
@@ -32,6 +32,7 @@
 #include <linux/sh_timer.h>
 #include <linux/slab.h>
 #include <linux/module.h>
+#include <linux/pm_domain.h>
 
 struct sh_tmu_priv {
 	void __iomem *mapbase;
@@ -410,6 +411,9 @@ static int __devinit sh_tmu_probe(struct
 	struct sh_tmu_priv *p = platform_get_drvdata(pdev);
 	int ret;
 
+	if (!is_early_platform_device(pdev))
+		pm_genpd_dev_always_on(&pdev->dev, true);
+
 	if (p) {
 		dev_info(&pdev->dev, "kept as earlytimer\n");
 		return 0;
Index: linux/arch/arm/mach-shmobile/setup-sh7372.c
=================================--- linux.orig/arch/arm/mach-shmobile/setup-sh7372.c
+++ linux/arch/arm/mach-shmobile/setup-sh7372.c
@@ -1043,6 +1043,8 @@ void __init sh7372_add_standard_devices(
 	sh7372_add_device_to_domain(&sh7372_a4r, &veu2_device);
 	sh7372_add_device_to_domain(&sh7372_a4r, &veu3_device);
 	sh7372_add_device_to_domain(&sh7372_a4r, &jpu_device);
+	sh7372_add_device_to_domain(&sh7372_a4r, &tmu00_device);
+	sh7372_add_device_to_domain(&sh7372_a4r, &tmu01_device);
 }
 
 void __init sh7372_add_early_devices(void)
Index: linux/drivers/clocksource/sh_cmt.c
=================================--- linux.orig/drivers/clocksource/sh_cmt.c
+++ linux/drivers/clocksource/sh_cmt.c
@@ -32,6 +32,7 @@
 #include <linux/sh_timer.h>
 #include <linux/slab.h>
 #include <linux/module.h>
+#include <linux/pm_domain.h>
 
 struct sh_cmt_priv {
 	void __iomem *mapbase;
@@ -689,6 +690,9 @@ static int __devinit sh_cmt_probe(struct
 	struct sh_cmt_priv *p = platform_get_drvdata(pdev);
 	int ret;
 
+	if (!is_early_platform_device(pdev))
+		pm_genpd_dev_always_on(&pdev->dev, true);
+
 	if (p) {
 		dev_info(&pdev->dev, "kept as earlytimer\n");
 		return 0;
Index: linux/drivers/clocksource/sh_mtu2.c
=================================--- linux.orig/drivers/clocksource/sh_mtu2.c
+++ linux/drivers/clocksource/sh_mtu2.c
@@ -31,6 +31,7 @@
 #include <linux/sh_timer.h>
 #include <linux/slab.h>
 #include <linux/module.h>
+#include <linux/pm_domain.h>
 
 struct sh_mtu2_priv {
 	void __iomem *mapbase;
@@ -306,6 +307,9 @@ static int __devinit sh_mtu2_probe(struc
 	struct sh_mtu2_priv *p = platform_get_drvdata(pdev);
 	int ret;
 
+	if (!is_early_platform_device(pdev))
+		pm_genpd_dev_always_on(&pdev->dev, true);
+
 	if (p) {
 		dev_info(&pdev->dev, "kept as earlytimer\n");
 		return 0;