linux-kernel - Re: [PATCH] i2c: core: helper function to detect slave mode

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Message-ID: <CAHp75VdB+pApFgjFOwWYYQFUmxv5k6OYKgB4fstuy=3=2QesBQ@mail.gmail.com>
Date:   Fri, 6 Jan 2017 18:29:44 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Luis Oliveira <Luis.Oliveira@...opsys.com>
Cc:     Wolfram Sang <wsa@...-dreams.de>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Jarkko Nikula <jarkko.nikula@...ux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        linux-i2c@...r.kernel.org, devicetree <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Ramiro.Oliveira@...opsys.com, Joao Pinto <Joao.Pinto@...opsys.com>,
        CARLOS.PALMINHA@...opsys.com
Subject: Re: [PATCH] i2c: core: helper function to detect slave mode

On Thu, Jan 5, 2017 at 7:24 PM, Luis Oliveira
<Luis.Oliveira@...opsys.com> wrote:
> This function has the purpose of mode detection by checking the
> device nodes for a reg matching with the I2C_OWN_SLAVE_ADDREESS flag.
> Currently only checks using OF functions (ACPI slave not supported yet).

The code looks good, one important comment below, after addressing it:

Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

P.S. Btw, we have Suggested-by tag for giving credit for suggestion.
Please use it.

> --- a/drivers/i2c/i2c-core.c
> +++ b/drivers/i2c/i2c-core.c
> @@ -3691,6 +3691,25 @@ int i2c_slave_unregister(struct i2c_client *client)

Please, add kernel doc description here, important thing is to explain
return codes in Return: section of it.

> +int i2c_slave_mode_detect(struct device *dev)
> +{

> +       struct device_node *child;
> +       u32 reg;

I would consider them as private to the OF branch. But it's really
minor and up to you (I don't remember if we have such style examples
in i2c core code).

> +
> +       if (IS_BUILTIN(CONFIG_OF) && dev->of_node) {
> +               for_each_child_of_node(dev->of_node, child) {
> +                       of_property_read_u32(child, "reg", &reg);
> +                       if (reg & I2C_OWN_SLAVE_ADDRESS)
> +                               return 1;
> +               }
> +       } else if (IS_BUILTIN(CONFIG_ACPI) && ACPI_HANDLE(dev)) {
> +               dev_dbg(dev, "ACPI slave is not supported yet\n");
> +       }
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(i2c_slave_mode_detect);

-- 
With Best Regards,
Andy Shevchenko