linux-kernel - Re: [PATCH v4] i2c: tegra: Add the ACPI support

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Date:   Thu, 25 Nov 2021 21:28:56 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Akhil R <akhilrajeev@...dia.com>
Cc:     Christian Koenig <christian.koenig@....com>,
        Dmitry Osipenko <digetx@...il.com>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        Jon Hunter <jonathanh@...dia.com>,
        Laxman Dewangan <ldewangan@...dia.com>,
        linaro-mm-sig@...ts.linaro.org,
        linux-i2c <linux-i2c@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        linux-tegra <linux-tegra@...r.kernel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Thierry Reding <thierry.reding@...il.com>
Subject: Re: [PATCH v4] i2c: tegra: Add the ACPI support

On Thu, Nov 25, 2021 at 6:54 PM Akhil R <akhilrajeev@...dia.com> wrote:
>
> Add support for the ACPI based device registration so that the driver
> can be also enabled through ACPI table.
>
> This does not include the ACPI support for Tegra VI and DVC I2C.

Thanks for an update, my comments below.

...

> -       err = reset_control_reset(i2c_dev->rst);
> +       if (handle)

> +               err = acpi_evaluate_object(handle, "_RST", NULL, NULL);

Does it compile for CONFIG_ACPI=n case?

> +       else
> +               err = reset_control_reset(i2c_dev->rst);

If not, you will need something like this instead:

#ifdef CONFIG_ACPI
               err = acpi_evaluate_object(ACPI_HANDLE(...), "_RST", NULL, NULL);
#else
               err = reset_control_reset(i2c_dev->rst);
#endif

...

> +       err = device_property_read_u32(i2c_dev->dev, "clock-frequency",
> +                                      &i2c_dev->bus_clk_rate);
>         if (err)
>                 i2c_dev->bus_clk_rate = I2C_MAX_STANDARD_MODE_FREQ;

Actually you need to switch to use i2c_timings data structure and
corresponding methods.
This change will be incorporated there. I.o.w. do it as a prerequisite
to this patch.

...

> +       if (ACPI_HANDLE(i2c_dev->dev))
> +               return 0;

With above mentioned ifdeffery this may be converted back to
has_acpi_companion() which is slightly better in this case.

> +       if (ACPI_HANDLE(i2c_dev->dev))
> +               return 0;

Ditto.

P.S> Sorry if I missed something in the previous reviews.

-- 
With Best Regards,
Andy Shevchenko