Re: [RFC/RFT PATCH 2/2] gpio: omap: ensure that runtime pm will disable unused gpio banks

[Tony Lindgren <tony@atomide.com>]

* Tony Lindgren <tony@atomide.com> [150319 16:08]:
> * Tony Lindgren <tony@atomide.com> [150307 00:08]:
> > * grygorii.strashko@linaro.org <grygorii.strashko@linaro.org> [150306 11:27]:
> > > From: Grygorii Strashko <grygorii.strashko@linaro.org>
> > > 
> > > Now there are two points related to Runtime PM usage:
> > > 1) bank state doesn't need to be checked in places where
> > > Rintime PM is used, bacause Runtime PM maintains its
> > > own usage counter:
> > >       if (!BANK_USED(bank))
> > >                pm_runtime_get_sync(bank->dev);
> > > so, it's safe to drop such checks.
> > > 
> > > 2) There is a call of pm_runtime_get_sync() in omap_gpio_irq_type(),
> > > but no corresponding put. As result, GPIO devices could be
> > > powered on forever if at least one GPIO was used as IRQ.
> > > Hence, allow powering off GPIO banks by adding missed
> > > pm_runtime_put(bank->dev) at the end of omap_gpio_irq_type().
> > 
> > Nice to see this happening, but I think before merging this we need
> > to test to be sure that the pm_runtime calls actually match.. I'm
> > not convinced right now.. We may still have uninitialized entry
> > points similar to 3d009c8c61f9 ("gpio: omap: Fix bad device
> > access with setup_irq()").
> 
> OK so I finally got around testing this along with your bank
> removal set. Looks like this patch causes a regression at least
> with n900 keyboard LEDs with off-idle. The LED won't come back
> on after restore from off-idle. Anyways, now we have something
> reproducable :) So I'll try to debug it further at some point,
> might be few days before I get to it.

Sorry for the delay, finally got around to this one :)

Here's what I came up with, only lightly tested so far. Note that
we need to keep the PM runtime per bank, not per GPIO. Will repost
a proper patch after some more testing.

This should not cause any functional changes, mostly just removal
of code that can all be done in omap_enable/disable_gpio_module.

Regards,

Tony

8< -------------------------
--- a/drivers/gpio/gpio-omap.c
+++ b/drivers/gpio/gpio-omap.c
@@ -86,6 +86,7 @@ struct gpio_bank {
 #define BANK_USED(bank) (bank->mod_usage || bank->irq_usage)
 #define LINE_USED(line, offset) (line & (BIT(offset)))
 
+static void omap_reset_gpio(struct gpio_bank *bank, unsigned offset);
 static void omap_gpio_unmask_irq(struct irq_data *d);
 
 static inline struct gpio_bank *omap_irq_data_get_bank(struct irq_data *d)
@@ -419,8 +420,16 @@ static int omap_set_gpio_triggering(struct gpio_bank *bank, int gpio,
 	return 0;
 }
 
-static void omap_enable_gpio_module(struct gpio_bank *bank, unsigned offset)
+static void omap_enable_gpio_module(struct gpio_bank *bank, unsigned offset,
+				    bool is_irq)
 {
+	unsigned long flags;
+
+	/* PM runtime is per bank, not per GPIO line */
+	if (!BANK_USED(bank))
+		pm_runtime_get_sync(bank->dev);
+
+	spin_lock_irqsave(&bank->lock, flags);
 	if (bank->regs->pinctrl) {
 		void __iomem *reg = bank->base + bank->regs->pinctrl;
 
@@ -438,11 +447,30 @@ static void omap_enable_gpio_module(struct gpio_bank *bank, unsigned offset)
 		writel_relaxed(ctrl, reg);
 		bank->context.ctrl = ctrl;
 	}
+
+	if (is_irq) {
+		omap_set_gpio_direction(bank, offset, 1);
+		bank->irq_usage |= BIT(offset);
+	} else {
+		omap_set_gpio_triggering(bank, offset, IRQ_TYPE_NONE);
+		bank->mod_usage |= BIT(offset);
+	}
+	spin_unlock_irqrestore(&bank->lock, flags);
 }
 
-static void omap_disable_gpio_module(struct gpio_bank *bank, unsigned offset)
+static void omap_disable_gpio_module(struct gpio_bank *bank, unsigned offset,
+				     bool is_irq)
 {
 	void __iomem *base = bank->base;
+	unsigned long flags;
+
+	spin_lock_irqsave(&bank->lock, flags);
+	if (is_irq)
+		bank->irq_usage &= ~(BIT(offset));
+	else
+		bank->mod_usage &= ~(BIT(offset));
+
+	omap_reset_gpio(bank, offset);
 
 	if (bank->regs->wkup_en &&
 	    !LINE_USED(bank->mod_usage, offset) &&
@@ -463,6 +491,11 @@ static void omap_disable_gpio_module(struct gpio_bank *bank, unsigned offset)
 		writel_relaxed(ctrl, reg);
 		bank->context.ctrl = ctrl;
 	}
+	spin_unlock_irqrestore(&bank->lock, flags);
+
+	/* PM runtime is per bank, not per GPIO line */
+	if (!BANK_USED(bank))
+		pm_runtime_put(bank->dev);
 }
 
 static int omap_gpio_is_input(struct gpio_bank *bank, unsigned offset)
@@ -472,15 +505,6 @@ static int omap_gpio_is_input(struct gpio_bank *bank, unsigned offset)
 	return readl_relaxed(reg) & BIT(offset);
 }
 
-static void omap_gpio_init_irq(struct gpio_bank *bank, unsigned offset)
-{
-	if (!LINE_USED(bank->mod_usage, offset)) {
-		omap_enable_gpio_module(bank, offset);
-		omap_set_gpio_direction(bank, offset, 1);
-	}
-	bank->irq_usage |= BIT(offset);
-}
-
 static int omap_gpio_irq_type(struct irq_data *d, unsigned type)
 {
 	struct gpio_bank *bank = omap_irq_data_get_bank(d);
@@ -488,9 +512,6 @@ static int omap_gpio_irq_type(struct irq_data *d, unsigned type)
 	unsigned long flags;
 	unsigned offset = d->hwirq;
 
-	if (!BANK_USED(bank))
-		pm_runtime_get_sync(bank->dev);
-
 	if (type & ~IRQ_TYPE_SENSE_MASK)
 		return -EINVAL;
 
@@ -498,13 +519,9 @@ static int omap_gpio_irq_type(struct irq_data *d, unsigned type)
 		(type & (IRQ_TYPE_LEVEL_LOW|IRQ_TYPE_LEVEL_HIGH)))
 		return -EINVAL;
 
+	omap_enable_gpio_module(bank, offset, true);
 	spin_lock_irqsave(&bank->lock, flags);
 	retval = omap_set_gpio_triggering(bank, offset, type);
-	omap_gpio_init_irq(bank, offset);
-	if (!omap_gpio_is_input(bank, offset)) {
-		spin_unlock_irqrestore(&bank->lock, flags);
-		return -EINVAL;
-	}
 	spin_unlock_irqrestore(&bank->lock, flags);
 
 	if (type & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
@@ -659,26 +676,8 @@ static int omap_gpio_wake_enable(struct irq_data *d, unsigned int enable)
 static int omap_gpio_request(struct gpio_chip *chip, unsigned offset)
 {
 	struct gpio_bank *bank = container_of(chip, struct gpio_bank, chip);
-	unsigned long flags;
 
-	/*
-	 * If this is the first gpio_request for the bank,
-	 * enable the bank module.
-	 */
-	if (!BANK_USED(bank))
-		pm_runtime_get_sync(bank->dev);
-
-	spin_lock_irqsave(&bank->lock, flags);
-	/* Set trigger to none. You need to enable the desired trigger with
-	 * request_irq() or set_irq_type(). Only do this if the IRQ line has
-	 * not already been requested.
-	 */
-	if (!LINE_USED(bank->irq_usage, offset)) {
-		omap_set_gpio_triggering(bank, offset, IRQ_TYPE_NONE);
-		omap_enable_gpio_module(bank, offset);
-	}
-	bank->mod_usage |= BIT(offset);
-	spin_unlock_irqrestore(&bank->lock, flags);
+	omap_enable_gpio_module(bank, offset, false);
 
 	return 0;
 }
@@ -686,20 +685,8 @@ static int omap_gpio_request(struct gpio_chip *chip, unsigned offset)
 static void omap_gpio_free(struct gpio_chip *chip, unsigned offset)
 {
 	struct gpio_bank *bank = container_of(chip, struct gpio_bank, chip);
-	unsigned long flags;
-
-	spin_lock_irqsave(&bank->lock, flags);
-	bank->mod_usage &= ~(BIT(offset));
-	omap_disable_gpio_module(bank, offset);
-	omap_reset_gpio(bank, offset);
-	spin_unlock_irqrestore(&bank->lock, flags);
 
-	/*
-	 * If this is the last gpio to be freed in the bank,
-	 * disable the bank module.
-	 */
-	if (!BANK_USED(bank))
-		pm_runtime_put(bank->dev);
+	omap_disable_gpio_module(bank, offset, false);
 }
 
 /*
@@ -788,15 +775,9 @@ exit:
 static unsigned int omap_gpio_irq_startup(struct irq_data *d)
 {
 	struct gpio_bank *bank = omap_irq_data_get_bank(d);
-	unsigned long flags;
 	unsigned offset = d->hwirq;
 
-	if (!BANK_USED(bank))
-		pm_runtime_get_sync(bank->dev);
-
-	spin_lock_irqsave(&bank->lock, flags);
-	omap_gpio_init_irq(bank, offset);
-	spin_unlock_irqrestore(&bank->lock, flags);
+	omap_enable_gpio_module(bank, offset, true);
 	omap_gpio_unmask_irq(d);
 
 	return 0;
@@ -805,21 +786,9 @@ static unsigned int omap_gpio_irq_startup(struct irq_data *d)
 static void omap_gpio_irq_shutdown(struct irq_data *d)
 {
 	struct gpio_bank *bank = omap_irq_data_get_bank(d);
-	unsigned long flags;
 	unsigned offset = d->hwirq;
 
-	spin_lock_irqsave(&bank->lock, flags);
-	bank->irq_usage &= ~(BIT(offset));
-	omap_disable_gpio_module(bank, offset);
-	omap_reset_gpio(bank, offset);
-	spin_unlock_irqrestore(&bank->lock, flags);
-
-	/*
-	 * If this is the last IRQ to be freed in the bank,
-	 * disable the bank module.
-	 */
-	if (!BANK_USED(bank))
-		pm_runtime_put(bank->dev);
+	omap_disable_gpio_module(bank, offset, true);
 }
 
 static void omap_gpio_ack_irq(struct irq_data *d)