linux-kernel - Re: [PATCH V2 10/12] gpio: tegra: implement wake event support for Tegra210 and prior GPIO

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Date:   Wed, 29 May 2019 16:03:18 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Sowjanya Komatineni <skomatineni@...dia.com>
Cc:     jonathanh@...dia.com, tglx@...utronix.de, jason@...edaemon.net,
        marc.zyngier@....com, linus.walleij@...aro.org, stefan@...er.ch,
        mark.rutland@....com, pdeschrijver@...dia.com, pgaikwad@...dia.com,
        sboyd@...nel.org, linux-clk@...r.kernel.org,
        linux-gpio@...r.kernel.org, jckuo@...dia.com, josephl@...dia.com,
        talho@...dia.com, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org, mperttunen@...dia.com,
        spatra@...dia.com, robh+dt@...nel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH V2 10/12] gpio: tegra: implement wake event support for
 Tegra210 and prior GPIO

On Tue, May 28, 2019 at 04:08:54PM -0700, Sowjanya Komatineni wrote:
> The GPIO controller doesn't have any controls to enable the system to
> wake up from low power states based on activity on GPIO pins. An extra
> hardware block that is part of the power management controller (PMC)
> contains these controls. In order for the GPIO controller to be able
> to cooperate with the PMC, obtain a reference to the PMC's IRQ domain
> and make it a parent to the GPIO controller's IRQ domain. This way the
> PMC gets an opportunity to program the additional registers required
> to enable wakeup sources on suspend.
> 
> Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
> ---
>  drivers/gpio/gpio-tegra.c | 116 +++++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 110 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-tegra.c b/drivers/gpio/gpio-tegra.c
> index 6d9b6906b9d0..5190129668d3 100644
> --- a/drivers/gpio/gpio-tegra.c
> +++ b/drivers/gpio/gpio-tegra.c
> @@ -32,6 +32,8 @@
>  #include <linux/pinctrl/consumer.h>
>  #include <linux/pm.h>
>  
> +#include <dt-bindings/interrupt-controller/arm-gic.h>
> +
>  #define GPIO_BANK(x)		((x) >> 5)
>  #define GPIO_PORT(x)		(((x) >> 3) & 0x3)
>  #define GPIO_BIT(x)		((x) & 0x7)
> @@ -275,8 +277,22 @@ static int tegra_gpio_set_config(struct gpio_chip *chip, unsigned int offset,
>  static int tegra_gpio_to_irq(struct gpio_chip *chip, unsigned int offset)
>  {
>  	struct tegra_gpio_info *tgi = gpiochip_get_data(chip);
> +	struct irq_domain *domain = tgi->irq_domain;
> +
> +	if (!gpiochip_irqchip_irq_valid(chip, offset))
> +		return -ENXIO;
> +
> +	if (irq_domain_is_hierarchy(domain)) {
> +		struct irq_fwspec spec;
> +
> +		spec.fwnode = domain->fwnode;
> +		spec.param_count = 2;
> +		spec.param[0] = offset;
> +		spec.param[1] = IRQ_TYPE_NONE;
> +		return irq_domain_alloc_irqs(domain, 1, NUMA_NO_NODE, &spec);

This looks like it was copied from the equivalent Tegra186 patch. I have
since then changed the implementation, based on feedback by Linus, to
not call irq_domain_alloc_irqs() here and instead call
irq_create_fwspec_mapping(). This has the advantage of not requiring the
irq_domain_alloc_irqs() function to be exported. It ends up calling that
function internally, but as discussed with Linus it's also a nicer way
to create these mappings.

> +	}
>  
> -	return irq_find_mapping(tgi->irq_domain, offset);
> +	return irq_find_mapping(domain, offset);
>  }
>  
>  static void tegra_gpio_irq_ack(struct irq_data *d)
> @@ -365,7 +381,10 @@ static int tegra_gpio_irq_set_type(struct irq_data *d, unsigned int type)
>  	else if (type & (IRQ_TYPE_EDGE_FALLING | IRQ_TYPE_EDGE_RISING))
>  		irq_set_handler_locked(d, handle_edge_irq);
>  
> -	return 0;
> +	if (d->parent_data)
> +		return irq_chip_set_type_parent(d, type);
> +	else
> +		return 0;

There's no need for this final else. Just make it a regular "return 0;"
at the end of the function, without the extra else branch.

>  }
>  
>  static void tegra_gpio_irq_shutdown(struct irq_data *d)
> @@ -503,6 +522,7 @@ static int tegra_gpio_irq_set_wake(struct irq_data *d, unsigned int enable)
>  	struct tegra_gpio_bank *bank = irq_data_get_irq_chip_data(d);
>  	unsigned int gpio = d->hwirq;
>  	u32 port, bit, mask;
> +	int ret;
>  
>  	port = GPIO_PORT(gpio);
>  	bit = GPIO_BIT(gpio);
> @@ -513,7 +533,14 @@ static int tegra_gpio_irq_set_wake(struct irq_data *d, unsigned int enable)
>  	else
>  		bank->wake_enb[port] &= ~mask;
>  
> -	return irq_set_irq_wake(bank->irq, enable);
> +	ret = irq_set_irq_wake(bank->irq, enable);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (d->parent_data)
> +		return irq_chip_set_wake_parent(d, enable);
> +	else
> +		return 0;

Same here.

Thierry

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