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

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Date:   Tue, 27 Oct 2020 18:46:39 +0800
From:   ChiYuan Huang <u0084500@...il.com>
To:     Pavel Machek <pavel@....cz>
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

Pavel Machek <pavel@....cz> 於 2020年10月27日 週二 下午6:15寫道：
>
> 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.
>
Yes, sure.
> > > > +     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.

Sorry, We don't focus on specific products. It's a general part flash
led controller.
I'll change it like as below
"It's commonly used in smartphones and tablets to assist the builtin camera."
>
> > > > +     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;"
Oh, I got it. redundant judgement.
>
> > > > +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 "&&" :-).
Thx.
>
> Best regards,
>                                                         Pavel
> --
> http://www.livejournal.com/~pavelmachek