linux-kernel - Re: [PATCHv3] media: i2c/adp1653: devicetree support for adp1653

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Date:	Fri, 3 Apr 2015 02:48:23 +0300
From:	Sakari Ailus <sakari.ailus@....fi>
To:	Pavel Machek <pavel@....cz>
Cc:	Andrew Morton <akpm@...l.org>, pali.rohar@...il.com,
	sre@...ian.org, sre@...g0.de,
	kernel list <linux-kernel@...r.kernel.org>,
	linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
	linux-omap@...r.kernel.org, tony@...mide.com, khilman@...nel.org,
	aaro.koskinen@....fi, ivo.g.dimitrov.75@...il.com,
	patrikbachan@...il.com, galak@...eaurora.org,
	bcousson@...libre.com, m.chehab@...sung.com,
	devicetree@...r.kernel.org
Subject: Re: [PATCHv3] media: i2c/adp1653: devicetree support for adp1653

Hi Pawel,

On Thu, Apr 02, 2015 at 10:30:44PM +0200, Pavel Machek wrote:
> Hi!
> 
> > Hi Pawel,
> > 
> > My apologies for the very late reply.
> > 
> > On Thu, Apr 02, 2015 at 04:38:46PM +0200, Pavel Machek wrote:
> > > 
> > > 
> > > We are moving to device tree support on OMAP3, but that currently
> > > breaks ADP1653 driver. This adds device tree support, plus required
> > > documentation.
> > > 
> > > Signed-off-by: Pavel Machek <pavel@....cz>
> > > 
> > > ---
> > > 
> > > I'm not sure if it is device tree or media framework, either everyone
> > > waits for someone else, or noone really cares.
> > 
> > Neither. Some people are unfortuantely very busy with many other things as
> > well. :-P
> 
> Well.. Being busy is ok. Nitpicking is also ok. But both at the same
> time... is not good. 

Good. Then we should be fine. :-)

> 
> > > Andrew, can you just merge it?
> > > 
> > > Please apply,
> > 
> > Please wait just a while.
> > 
> > I think we can merge this eventually through the linux-media tree, but
> > please first see the comments below.
> > 
> 
> > > +Required properties of the flash LED child node:
> > > +
> > > +- flash-max-microamp : see Documentation/devicetree/bindings/leds/common.txt
> > > +- flash-timeout-us : see Documentation/devicetree/bindings/leds/common.txt
> > 
> > The documentation says that the maximum value is used if these values are
> > not specified. I think I'd make these optional.
> 
> I'd rather not: when you make a typo in dts, it would supply maximum
> available current, potentially damaging the LED. You will not be able
> to tell brightness difference with naked eye...

Fine for me.

> > >  __adp1653_set_power(struct adp1653_flash *flash, int on)
> > >  {
> > > -	int ret;
> > > +	int ret = 0;
> > > +
> > > +	if (flash->platform_data->power) {
> > > +		ret = flash->platform_data->power(&flash->subdev, on);
> > 
> > The power() callback should be dropped. It's controlling a GPIO. But that
> > can be done later on. The alternative is a patch before this one.
> 
> I'd prefer to do it later; we want to keep functionality on N900
> without DTS, too.

Fine as well.

> > >  	flash = devm_kzalloc(&client->dev, sizeof(*flash), GFP_KERNEL);
> > >  	if (flash == NULL)
> > >  		return -ENOMEM;
> > >  
> > >  	flash->platform_data = client->dev.platform_data;
> > > +	if (!flash->platform_data) {
> > 
> > I'd check whether dev->of_node is non-NULL instead.
> 
> Ok.
> 
> > > @@ -438,10 +510,10 @@ static int adp1653_probe(struct i2c_client *client,
> > >  		goto free_and_quit;
> > >  
> > >  	flash->subdev.entity.type = MEDIA_ENT_T_V4L2_SUBDEV_FLASH;
> > > -
> > 
> > I rather liked the newline here. Please don't remove it. :-)
> 
> Ok.
> 
> > > @@ -464,7 +536,7 @@ static const struct i2c_device_id adp1653_id_table[] = {
> > >  };
> > >  MODULE_DEVICE_TABLE(i2c, adp1653_id_table);
> > >  
> > > -static struct dev_pm_ops adp1653_pm_ops = {
> > > +static const struct dev_pm_ops adp1653_pm_ops = {
> > >  	.suspend	= adp1653_suspend,
> > >  	.resume		= adp1653_resume,
> > >  };
> > >  
> > > 
> > 
> > A corresponding change to the N900 dts would be very nice.
> 
> Corresponding change to the dts will come in separate patch. Or do you
> have n900 for testing?

Yes, it should be a separate patch, I agree.

I do have one but I can't say when I'd have time to test it. I'm fine with
you having tested it though.

> > I think you're missing change to adp1653_i2c_driver.driver.of_match_table.
> 
> It actually worked for me, which means device tree somehow does it
> magic.

By magic? :-) It probably just ends up comparing the device and the driver
names. How about adding the of_match_table?

-- 
Regards,

Sakari Ailus
e-mail: sakari.ailus@....fi	XMPP: sailus@...iisi.org.uk
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