linux-kernel - Re: [PATCH v1 1/2] leds: rt4505: Add support for Richtek RT4505 flash led controller

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Message-ID: <20201027101535.GB13900@duo.ucw.cz>
Date:   Tue, 27 Oct 2020 11:15:35 +0100
From:   Pavel Machek <pavel@....cz>
To:     ChiYuan Huang <u0084500@...il.com>
Cc:     dmurphy@...com, robh+dt@...nel.org, linux-leds@...r.kernel.org,
        lkml <linux-kernel@...r.kernel.org>,
        cy_huang <cy_huang@...htek.com>, devicetree@...r.kernel.org
Subject: Re: [PATCH v1 1/2] leds: rt4505: Add support for Richtek RT4505
 flash led controller

Hi!

> > Please use upper-case "LED" everywhere.
> >
> > This should be 2nd in the series, after DT changes.
> Sure, will ack in next series patch.

Feel free to wait for dt ACKs before resending.

> > > +     help
> > > +       This option enables support for the RT4505 flash led controller.
> >
> > Information where it is used would be welcome here.
> How about to add the below line for the extra information?
> Usually used to company with the camera device on smartphone/tablet
> products

Yes, that would help.

"It is commonly used in smartphones, such as Bell Packard T899" would
be even better.

> > > +     ret = regmap_update_bits(priv->regmap, RT4505_REG_ENABLE, RT4505_ENABLE_MASK, val);
> > > +
> > > +unlock:
> > > +     mutex_unlock(&priv->lock);
> > > +     return ret;
> > > +}
> >
> > Why is the locking needed? What will the /sys/class/leds interface
> > look like on system with your flash?
> 
> The original thought is because there's still another way to control
> flash like as v4l2.
> But after reviewing the source code, led sysfs node will be protected
> by led_cdev->led_access.
> And V4L2 flash will also be protected by v4l2_fh_is_singular API.
> I think the whole locking in the source code code may be removed. Right?

Well, maybe you need it, I did not check..

What will the /sys/class/leds interface look like on system with your flash?

> > > +     *state = ((val & RT4505_FLASH_GET) == RT4505_FLASH_GET) ? true : false;
> >
> > No need for ? ... part.
> Do you mean this function is not needed? If yes, it can be removed.
> But if it removed, led sysfs flash_strobe show will be not supported.

I meant "replace line with: *state = (val & RT4505_FLASH_GET) == RT4505_FLASH_GET;"

> > > +static bool rt4505_is_accessible_reg(struct device *dev, unsigned int reg)
> > > +{
> > > +     if (reg == RT4505_REG_RESET || (reg >= RT4505_REG_CONFIG  && reg <= RT4505_REG_FLAGS))
> > > +             return true;
> >
> > Make this two stagements.
> Like as the below one?? Or separate it into two if case.
> if (reg == RT4505_REG_RESET ||
>        reg >= RT4505_REG_CONFIG  && reg <= RT4505_REG_FLAGS))

That would be fine, too... if you use just one space before "&&" :-).

Best regards,
							Pavel
-- 
http://www.livejournal.com/~pavelmachek

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