linux-kernel - Re: i2c: xiic: Strange clk_prepare_enable() in xiic_i2c

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Message-ID: <CAKfKVtE5NC8L6gi642FhKQKvs-Lnmi4eqVkE6-9FQu=FEnno1A@mail.gmail.com>
Date:   Sat, 17 Dec 2016 12:36:19 +0530
From:   Shubhrajyoti Datta <shubhrajyoti.datta@...il.com>
To:     Alexey Khoroshilov <khoroshilov@...ras.ru>
Cc:     Shubhrajyoti Datta <shubhraj@...inx.com>,
        Rob Herring <robh@...nel.org>,
        Wolfram Sang <wsa@...-dreams.de>, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org, ldv-project@...uxtesting.org
Subject: Re: i2c: xiic: Strange clk_prepare_enable() in xiic_i2c_remove()

On Sat, Dec 17, 2016 at 3:24 AM, Alexey Khoroshilov
<khoroshilov@...ras.ru> wrote:
> Dear Shubhrajyoti,
>
> Looking at 36ecbcab84d0 ("i2c: xiic: Implement power management")
> it is not clear why clk_prepare_enable(i2c->clk) is required in
> xiic_i2c_remove()?

834         ret = clk_prepare_enable(i2c->clk);
835         if (ret) {
836                 dev_err(&pdev->dev, "Unable to enable clock.\n");
837                 return ret;
838         }
839         xiic_deinit(i2c);
840         clk_disable_unprepare(i2c->clk);

so it is enabled and disabled after xiic_deinit.

>
> It is enabled in xiic_i2c_probe() and disabled/enabled in
> cdns_i2c_runtime_suspend()/cdns_i2c_runtime_resume().
>
> Could you please clarify the point.
>
> --
> Alexey Khoroshilov
> Linux Verification Center, ISPRAS
> web: http://linuxtesting.org
>
> --
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