linux-kernel - Re: [PATCH v4 1/2] i2c: davinci: Add PM Runtime Support

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Message-ID: <CAMz4ku+_saDS8VBf1kXb+HMDqvx2O2o4qwcU4dEjFvtyE_9JKg@mail.gmail.com>
Date:   Tue, 12 Sep 2017 17:14:42 +0800
From:   Baolin Wang <baolin.wang@...aro.org>
To:     Sekhar Nori <nsekhar@...com>
Cc:     Franklin S Cooper Jr <fcooper@...com>,
        Wolfram Sang <wsa@...-dreams.de>,
        Rob Herring <robh+dt@...nel.org>, linux@...linux.org.uk,
        linux-i2c@...r.kernel.org, devicetree@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        linux-arm-kernel@...ts.infradead.org, grygorii.strashko@...com,
        vigneshr@...com
Subject: Re: [PATCH v4 1/2] i2c: davinci: Add PM Runtime Support

Hi,

On 12 September 2017 at 16:48, Sekhar Nori <nsekhar@...com> wrote:
> On Tuesday 12 September 2017 07:28 AM, Baolin Wang wrote:
>>> @@ -802,13 +821,24 @@ static int davinci_i2c_probe(struct platform_device *pdev)
>>>         dev->clk = devm_clk_get(&pdev->dev, NULL);
>>>         if (IS_ERR(dev->clk))
>>>                 return PTR_ERR(dev->clk);
>>> -       clk_prepare_enable(dev->clk);
>
>> You removed clk enable here, I think it can not work if we did not
>> open CONFIG_PM macro. I think you should keep clk enable here, and set
>
> What do you mean by "open CONFIG_PM macro" ?

If you did not open CONFIG_PM macro, then the pm_runtime_xxx() will be
dummy functions, but now the i2c driver can not work since you did not
enable clock, right?

>
>> rpm active by pm_runtime_set_active() before issuing
>> pm_runtime_enable().
>
> Can you explain why you want to do this instead of relying on
> pm_runtime_get_sync() to enable clock?

What I mean is you should compatible whether CONFIG_PM is enabled or not.

-- 
Baolin.wang
Best Regards