[PATCH v4 2/3] power: domain: handle genpd correctly when needing interrupts

[Martin Kepplinger]

If for example the power-domains' power-supply node (regulator) needs
interrupts to work, the current setup with noirq callbacks cannot
work; for example a pmic regulator on i2c, when suspending, usually already
times out during suspend_noirq:

[   41.024193] buck4: failed to disable: -ETIMEDOUT

So fix system suspend and resume for these power-domains by using the
"outer" suspend/resume callbacks instead. Tested on the imx8mq-librem5 board,
but by looking at the dts, this will fix imx8mq-evk and possibly many other
boards too.

This is designed so that genpd providers just say "this genpd needs
interrupts" (by setting the flag) - without implying an implementation.

Initially system suspend problems had been discussed at
https://lore.kernel.org/linux-arm-kernel/20211002005954.1367653-8-l.stach@pengutronix.de/
which led to discussing the pmic that contains the regulators which
serve as power-domain power-supplies:
https://lore.kernel.org/linux-pm/573166b75e524517782471c2b7f96e03fd93d175.camel@puri.sm/T/

Signed-off-by: Martin Kepplinger <martin.kepplinger at puri.sm>
---
 drivers/base/power/domain.c | 13 +++++++++++++
 include/linux/pm_domain.h   |  5 +++++
 2 files changed, 18 insertions(+)

diff --git a/drivers/base/power/domain.c b/drivers/base/power/domain.c
index 739e52cd4aba..76ea39e960f3 100644
--- a/drivers/base/power/domain.c
+++ b/drivers/base/power/domain.c
@@ -130,6 +130,7 @@ static const struct genpd_lock_ops genpd_spin_ops = {
 #define genpd_is_active_wakeup(genpd)	(genpd->flags & GENPD_FLAG_ACTIVE_WAKEUP)
 #define genpd_is_cpu_domain(genpd)	(genpd->flags & GENPD_FLAG_CPU_DOMAIN)
 #define genpd_is_rpm_always_on(genpd)	(genpd->flags & GENPD_FLAG_RPM_ALWAYS_ON)
+#define genpd_irq_on(genpd)		(genpd->flags & GENPD_FLAG_IRQ_ON)
 
 static inline bool irq_safe_dev_in_sleep_domain(struct device *dev,
 		const struct generic_pm_domain *genpd)
@@ -2076,6 +2077,13 @@ int pm_genpd_init(struct generic_pm_domain *genpd,
 		genpd->dev_ops.start = pm_clk_resume;
 	}
 
+	if (genpd_irq_on(genpd)) {
+		genpd->domain.ops.suspend = genpd_suspend_noirq;
+		genpd->domain.ops.resume = genpd_resume_noirq;
+		genpd->domain.ops.suspend_noirq = NULL;
+		genpd->domain.ops.resume_noirq = NULL;
+	}
+
 	/* The always-on governor works better with the corresponding flag. */
 	if (gov == &pm_domain_always_on_gov)
 		genpd->flags |= GENPD_FLAG_RPM_ALWAYS_ON;
@@ -2766,6 +2774,11 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
 			goto err;
 		dev_gpd_data(dev)->default_pstate = pstate;
 	}
+
+	if (pd->domain.ops.suspend_noirq && (pd->flags & GENPD_FLAG_IRQ_ON))
+		dev_err(dev, "PM domain %s needs irqs but uses noirq suspend\n",
+			pd->name);
+
 	return 1;
 
 err:
diff --git a/include/linux/pm_domain.h b/include/linux/pm_domain.h
index 76bc9e3ef5ff..03bb86e43550 100644
--- a/include/linux/pm_domain.h
+++ b/include/linux/pm_domain.h
@@ -61,6 +61,10 @@
  * GENPD_FLAG_MIN_RESIDENCY:	Enable the genpd governor to consider its
  *				components' next wakeup when determining the
  *				optimal idle state.
+ *
+ * GENPD_FLAG_IRQ_ON:		genpd needs irqs to be able to manage power
+ *				on/off. Use the outer suspend/resume callbacks
+ *				instead of noirq for example.
  */
 #define GENPD_FLAG_PM_CLK		BIT(0)
 #define GENPD_FLAG_IRQ_SAFE		BIT(1)
@@ -69,6 +73,7 @@
 #define GENPD_FLAG_CPU_DOMAIN		BIT(4)
 #define GENPD_FLAG_RPM_ALWAYS_ON	BIT(5)
 #define GENPD_FLAG_MIN_RESIDENCY	BIT(6)
+#define GENPD_FLAG_IRQ_ON		BIT(7)
 
 enum gpd_status {
 	GENPD_STATE_ON = 0,	/* PM domain is on */
-- 
2.30.2