linux-kernel - Re: [PATCH v4 3/3] media: ov7670: Add the s

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Message-ID: <20170918132649.njqvbs3zq6b5iuej@valkosipuli.retiisi.org.uk>
Date:   Mon, 18 Sep 2017 16:26:49 +0300
From:   Sakari Ailus <sakari.ailus@....fi>
To:     "Yang, Wenyou" <Wenyou.Yang@...rochip.com>
Cc:     Jonathan Corbet <corbet@....net>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        Linux Media Mailing List <linux-media@...r.kernel.org>,
        Mauro Carvalho Chehab <mchehab@...pensource.com>
Subject: Re: [PATCH v4 3/3] media: ov7670: Add the s_power operation

Hi Wenyou,

On Mon, Sep 18, 2017 at 05:26:16PM +0800, Yang, Wenyou wrote:
> Hi Sakari,
> 
> 
> On 2017/9/18 15:35, Sakari Ailus wrote:
> > Hi Wenyou,
> > 
> > Thanks for the update.
> > 
> > The driver exposes controls that are accessible through the sub-device node
> > even if the device hasn't been powered on.
> > 
> > Many ISP and bridge drivers will also power the sensor down once the last
> > user of the user space device nodes disappears. You could keep the device
> > powered at all times or change the behaviour so that controls can be
> > accessed when the power is off.
> > 
> > The best option would be to convert the driver to use runtime PM.
> Yes, I agree with you.
> I also noticed there are a lot of things needed to improve except for it,
> such as the platform data via device tree.
> I would like do it in another patch set. I will continue to work on it.

Adding runtime PM support later on sound good to me.

> > An example of this can be found in drivers/media/i2c/ov13858.c .
> A good example, thank you for your providing.

-- 
Sakari Ailus
e-mail: sakari.ailus@....fi