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

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Date:   Tue, 12 Sep 2017 14:52:02 +0530
From:   Sekhar Nori <nsekhar@...com>
To:     Baolin Wang <baolin.wang@...aro.org>
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

On Tuesday 12 September 2017 02:44 PM, Baolin Wang wrote:
> 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?

Ah, okay. I am not sure thats a concern on platforms on which this
driver is used. Without PM runtime support, most likely the platforms
will not boot and multiple drivers will fail.

Thanks,
Sekhar