Subject: [PATCH 1/1] gpio: omap: Fix PM runtime issue and remove most BANK_USED macros

From: [email-masked] ([email-masked])
Date: Sat, 02 May 2015 19:27:53 +0300

Hi Tony,

On 05/01/2015 12:12 AM, Tony Lindgren wrote:
> * Grygorii.Strashko at linaro.org <[email-masked]> [150430 12:12]:
>> On 04/29/2015 05:26 PM, Tony Lindgren wrote:
>>>
>>> In general removing 30 lines of duplicate code to fix freeing
>>> of resources makes sense :) I'd rather do that than add more similar
>>> code to fix it for sure. That will make further changes easier too.
>>
>> Unfortunately I'm not sure ( at least not for this driver.
>> Future fixes most probably will eat all these removed lines and
>> will just add anther "if else" but in different places (see description or corner case below).
>>
>> In my opinion, It might be better to review each interface function first as for GPIO chip
>> as for GPIOIRQ chip and ensure that they are doing exactly what need to be done
>> (as part this job - get rid of over-optimized functions like omap_reset_gpio or
>> omap_gpio_init_irq). And after that do further optimization.
> 
> In general I agree that a minimal fix is preferred. Unfortunately in
> this case "fixing" it gets us deeper into the mess with BANK_USED :)
>   
>> --- a/drivers/gpio/gpio-omap.c
>> +++ b/drivers/gpio/gpio-omap.c
>> @@ -488,9 +488,6 @@ 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 +495,11 @@ static int omap_gpio_irq_type(struct irq_data *d, unsigned type)
>>                  (type & (IRQ_TYPE_LEVEL_LOW|IRQ_TYPE_LEVEL_HIGH)))
>>                  return -EINVAL;
>>   
>> +       if (!BANK_USED(bank))
>> +               pm_runtime_get_sync(bank->dev);
>> +
>>          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))
>> @@ -512,6 +507,9 @@ static int omap_gpio_irq_type(struct irq_data *d, unsigned type)
>>          else if (type & (IRQ_TYPE_EDGE_FALLING | IRQ_TYPE_EDGE_RISING))
>>                  __irq_set_handler_locked(d->irq, handle_edge_irq);
>>   
>> +       if (!BANK_USED(bank))
>> +               pm_runtime_put(bank->dev);
>> +
>>          return retval;
>>   }
> 
> Hmm I don't think we can remove the call to omap_gpio_init_irq as with
> request_irq there's nothing ensuring the GPIO line is configured in
> the device tree case for example?
> 
> And then removing the check for omap_gpio_is_input is not good.. We
> should just call omap_set_gpio_direction to set it to input instead
> like I'm doing.

I think, We can remove all these calls from omap_gpio_irq_type() because
the following call sequence is executed when IRQ is requested:

 request_threaded_irq() - or - __irq_set_handler(is_chained==true)
 __setup_irq()
 irq_startup()
 desc->irq_data.chip->irq_startup()
 omap_gpio_irq_startup()
   omap_gpio_init_irq()
   omap_gpio_unmask_irq()

The check for omap_gpio_is_input should be done in startup omap_gpio_irq_startup()
in case if GPIO was requested before, and if not - GPIO should be configured as input.
(we just need to continue reviewing process as for me)

> 
> And looking at it more, omap_set_gpio_triggering can fail so we should
> check the return value (also with my patch). And if that fails, then we
> currently need a flag to keep track if we enabled the bank in
> omap_gpio_irq_type or not.. So piling up yet more BANK_USED tinkering.
> 
> I still think we're better of just removing it all. Below is my patch
> updated with the omap_set_gpio_triggering error handling. We can just
> make omap_enable_gpio_module return a value, it might provide us with
> more info where things go wrong :)
> 
>> There is another corner case :) - easy to reproduce
>> and it's present in old code.
>>
>> GPIOn is used as IRQ by some dev:
>> - in my case PCF8575.INT ->  gpio6.11
>> - PCFx driver knows nothing about type of IRQ line (GPIO or not)
>>    so it doesn't request gpio and just do request_irq()
>>
>> If I'll export gpio6.11 through sysfs and then unxeport it
>> then IRQs from PCFx will not be received any more.
>>
>> Seems omap_reset_gpio has to be split for GPIO and GPIO-IRQ cases.
> 
> OK, that sounds like a separate fix though if I understand your
> right. We should not allow exporting GPIOs to sysfs if they are
> being used.

Why not? It's good for IRQ debugging at least, but changing of GPIO
direction should be prohibited.

> 
> Regards,
> 
> Tony
> 
> 8< -------------------------
> From: Tony Lindgren <[email-masked]>
> Date: Mon, 27 Apr 2015 10:18:17 -0700
> Subject: [PATCH] gpio: omap: Fix PM runtime issue and remove most BANK_USED
>   macros
> 
> Looks like omap_gpio_irq_type can return early at several places
> leaving a GPIO bank enabled without doing pm_runtime_put if wrong
> GPIO arguments are passed.
> 
> Instead of adding more complicated BANK_USED macros, let's fix the
> issue properly. We can pass is_irq flag to omap_enable_gpio_module
> and omap_disble_gpio_module. And with that we can remove all the
> similar code elsewhere to get rid of most BANK_USED macros.
> 
> Note that the reason for the BANK_USED macro is that we need to manage
> PM runtime on per GPIO bank basis. In the long run we want to move to
> using PM runtime counts for each GPIO line to determine if a GPIO
> bank is used. Once we have a solution for omap_enable_gpio_module
> and omap_disable_gpio_module, we can remove the remaining BANK_USED
> macros.
> 
> Cc: Felipe Balbi <[email-masked]>
> Cc: Javier Martinez Canillas <[email-masked]>
> Cc: Grygorii Strashko <[email-masked]>
> Cc: Kevin Hilman <[email-masked]>
> Cc: Nishanth Menon <[email-masked]>
> Cc: Santosh Shilimkar <[email-masked]>
> Signed-off-by: Tony Lindgren <[email-masked]>
> 
> --- 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 +420,17 @@ 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 int omap_enable_gpio_module(struct gpio_bank *bank, unsigned offset,
> +				   bool is_irq)
>   {
> +	unsigned long flags;
> +	int error;
> +
> +	/* 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 +448,50 @@ 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);

This part will not work in the same way how it was before:
 omap_gpio_irq_startup
 - > omap_gpio_init_irq()
	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);

now:
 omap_gpio_irq_startup 
 - > omap_enable_gpio_module
 	if (is_irq) {
		omap_set_gpio_direction(bank, offset, 1);
		bank->irq_usage |= BIT(offset)

So, GPIO direction will be changed to INPUT with regards of its
current state.

> +	} else {
> +		/*
> +		 * 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)) {
> +			error = omap_set_gpio_triggering(bank, offset,
> +							 IRQ_TYPE_NONE);
> +			if (error)
> +				goto out_err;
> +		}
> +		bank->mod_usage |= BIT(offset);
> +	}
> +	spin_unlock_irqrestore(&bank->lock, flags);
> +
> +	return 0;
> +
> +out_err:
> +	dev_err(bank->dev, "enable failed with %i\n", error);
> +	if (!BANK_USED(bank))
> +		pm_runtime_put(bank->dev);
> +	spin_unlock_irqrestore(&bank->lock, flags);

unlock should be before pm_runtime call

> +
> +	return error;
>   }
>   
> -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 +512,11 @@ 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 +526,6 @@ 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 +533,6 @@ 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 +540,11 @@ static int omap_gpio_irq_type(struct irq_data *d, unsigned type)
>   		(type & (IRQ_TYPE_LEVEL_LOW|IRQ_TYPE_LEVEL_HIGH)))
>   		return -EINVAL;
>   
> +	retval = omap_enable_gpio_module(bank, offset, true);
> +	if (retval)
> +		return retval;
>   	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);

Your change will still not allow to switch off GPIO banks if at least one GPIO was used as IRQ.
Actually may be issue you've mentioned before
"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"

depends on the fact that my prev patch really allows GPIO bank to be switched of
during off-idle cycle (http://patchwork.ozlabs.org/patch/447416/). 

>   
>   	if (type & (IRQ_TYPE_LEVEL_LOW | IRQ_TYPE_LEVEL_HIGH))
> @@ -659,26 +699,11 @@ 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;
> +	int error;
>   
> -	/*
> -	 * 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);
> +	error = omap_enable_gpio_module(bank, offset, false);
> +	if (error)
> +		return error;
>   
>   	return 0;
>   }
> @@ -686,20 +711,8 @@ 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 +801,12 @@ 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;
> +	int error;
>   
> -	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);
> +	error = omap_enable_gpio_module(bank, offset, true);
> +	if (error)
> +		return error;
>   	omap_gpio_unmask_irq(d);
>   
>   	return 0;
> @@ -805,21 +815,9 @@ 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);
>   }

-- 
regards,
-grygorii