linux-kernel - Re: [PATCH] gpio: Add Tegra186 support

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Message-ID: <5836FCCF.1030109@nvidia.com>
Date:   Thu, 24 Nov 2016 20:14:31 +0530
From:   Laxman Dewangan <ldewangan@...dia.com>
To:     Thierry Reding <thierry.reding@...il.com>
CC:     Linus Walleij <linus.walleij@...aro.org>,
        Stephen Warren <swarren@...dotorg.org>,
        Suresh Mangipudi <smangipudi@...dia.com>,
        "Alexandre Courbot" <gnurou@...il.com>,
        <linux-kernel@...r.kernel.org>, <linux-gpio@...r.kernel.org>,
        <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH] gpio: Add Tegra186 support


On Thursday 24 November 2016 08:14 PM, Thierry Reding wrote:
> * PGP Signed by an unknown key
>
> On Thu, Nov 24, 2016 at 12:23:56PM +0530, Laxman Dewangan wrote:
>> On Tuesday 22 November 2016 11:25 PM, Thierry Reding wrote:
>>> +static inline struct tegra_gpio *to_tegra_gpio(struct gpio_chip *chip)
>>> +{
>>> +	return container_of(chip, struct tegra_gpio, gpio);
>>> +}
>> You dont need this as gpiochip_get_data(chip); can provide the required
>> driver specific data.
> It's common practice to embed the struct gpio_chip within a driver-
> specific structure, and it's equally common to use a container_of() to
> get at the embedding structure.

I am saying that you dont need this new APIs, GPIO framework already 
support this via the call gpiochip_get_data(chip); which you provided 
when adding gpiochip().



>
>>> +	gpio->gpio.parent = &pdev->dev;
>>> +
>>> +	gpio->gpio.get_direction = tegra186_gpio_get_direction;
>>> +	gpio->gpio.direction_input = tegra186_gpio_direction_input;
>>> +	gpio->gpio.direction_output = tegra186_gpio_direction_output;
>>> +	gpio->gpio.get = tegra186_gpio_get,
>>> +	gpio->gpio.set = tegra186_gpio_set;
>>> +	gpio->gpio.to_irq = tegra186_gpio_to_irq;
>>> +
>>> +	gpio->gpio.base = -1;
>>> +
>>> +	for (i = 0; i < gpio->soc->num_ports; i++)
>>> +		gpio->gpio.ngpio += gpio->soc->ports[i].pins;
>>> +
>> Our DT binding does not say this. We assume that we have 8 gpios per port.
>> so this will not work at all.
> This has nothing to do with the device tree binding. What the device
> tree binding defines is the indices to use to obtain a given GPIO within
> a given port. What numbering the driver uses internally is completely up
> to the driver implementation.
>
> Oh, and the above works just fine.


Nop, it will not work. The reason is:
include/dt-binding/gpio/tegra186-gpio.h


#define TEGRA_MAIN_GPIO(port, offset) \
         ((TEGRA_MAIN_GPIO_PORT_##port * 8) + offset)


so in your DTS file, if you use this macro for the gpio number then you 
will have pin per port as 8.
And so your total GPIO is 23 *8 (Port CC) but in source code ngpio is 
very less.