linux-kernel - Re: [PATCH v3 1/2] leds: mt6360: Add LED driver for MT6360

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Date:   Thu, 10 Sep 2020 22:25:10 +0200
From:   Pavel Machek <pavel@....cz>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>
Cc:     Gene Chen <gene.chen.richtek@...il.com>, robh+dt@...nel.org,
        Matthias Brugger <matthias.bgg@...il.com>,
        Dan Murphy <dmurphy@...com>, linux-leds@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Gene Chen <gene_chen@...htek.com>, Wilma.Wu@...iatek.com,
        shufan_lee@...htek.com, cy_huang@...htek.com,
        benjamin.chao@...iatek.com
Subject: Re: [PATCH v3 1/2] leds: mt6360: Add LED driver for MT6360

Hi!

> > > 1. set FLED1 brightness
> > > # echo 1 > /sys/class/leds/white:flash1/flash_brightness
> > > 2. enable FLED1 strobe
> > > # echo 1 > /sys/class/leds/white:flash1/flash_strobe
> > > 3 . turn off FLED1 strobe (just used to gaurantee the strobe mode
> > > flash leds must be turned off)
> > > # echo 0 > /sys/class/leds/white:flash1/flash_strobe
> > 
> > I believe I'd preffer only exposing torch functionality in
> > /sys/class/leds. .. strobe can be supported using v4l2 APIs.
> 
> Actually having LED flash class without strobe is pointless.
> If you looked at led_classdev_flash_register_ext() you would see that
> it fails with uninitialized strobe_set op. And V4L2 API for strobing
> flash calls strobe_set from LED flash class beneath.
> 
> That was the idea behind LED and V4L2 flash API unification - there
> is one hardware driver needed, the V4L2 Flash layer just takes over
> control over it when needed.

I agree that one driver is enough.

But we should not need flash_strobe file in sysfs. Simply use V4L2 for
that.

Best regards,
								Pavel