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From:   Gene Chen <gene.chen.richtek@gmail.com>
Date:   Fri, 11 Sep 2020 07:24:31 +0800
Message-ID: <CAE+NS34aKmu0tjnCPg3nF_vB0ELKsKwZSOeEXsm5V9aPAqqSbQ@mail.gmail.com>
Subject: Re: [PATCH v3 1/2] leds: mt6360: Add LED driver for MT6360
To:     Pavel Machek <pavel@ucw.cz>
Cc:     Jacek Anaszewski <jacek.anaszewski@gmail.com>, robh+dt@kernel.org,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Dan Murphy <dmurphy@ti.com>, linux-leds@vger.kernel.org,
        devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
        Gene Chen <gene_chen@richtek.com>, Wilma.Wu@mediatek.com,
        shufan_lee@richtek.com, cy_huang@richtek.com,
        benjamin.chao@mediatek.com
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Pavel Machek <pavel@ucw.cz> =E6=96=BC 2020=E5=B9=B49=E6=9C=8811=E6=97=A5 =
=E9=80=B1=E4=BA=94 =E4=B8=8B=E5=8D=883:05=E5=AF=AB=E9=81=93=EF=BC=9A
>
> Hi!
>
> > >+{
> > >+    struct mt6360_led *led =3D container_of(lcdev, struct mt6360_led,=
 flash.led_cdev);
> > >+    struct mt6360_priv *priv =3D led->priv;
> > >+    u32 enable_mask =3D MT6360_TORCHEN_MASK | MT6360_FLCSEN_MASK(led-=
>led_no);
> > >+    u32 val =3D (level) ? MT6360_FLCSEN_MASK(led->led_no) : 0;
> > >+    u32 prev =3D priv->fled_torch_used, curr;
> > >+    int ret;
> > >+
> > >+    dev_dbg(lcdev->dev, "[%d] brightness %d\n", led->led_no, level);
> > >+    if (priv->fled_strobe_used) {
> > >+            dev_warn(lcdev->dev, "Please disable strobe first [%d]\n"=
, priv->fled_strobe_used);
> >
> > Doesn't hardware handle that? IOW, what happens when you have enabled
> > both torch and flash? If flash just overrides torch mode, than you
> > should not prevent enabling torch in this case.
>
> Yep, this is strange/confusing... and was reason why I asked for not
> supporting strobe from sysfs.
>
> Could I get you to remove code you are not commenting at when
> reviewing?
>

MT6360 FLED register define is STROBE_EN/TORCH_EN/CS1/CS2 (current
source) 4 bits.
The STROBE_EN/TORCH_EN is shared by FLED1 and FLED2.
If I want to enable FLED1 torch mode, I set TORCH_EN and CS1
If I want to enable FLED2 strobe mode, I set STROBE_EN and CS2
For example I set FLED1 torch, then I set FLED2 strobe.
When I set FLED2 strobe, I will see the strobe current is FLED2 add
FLED1 current which is not I want.
So I need disable FLED1 torch first.
Considering every circumstances is complicated when share same H/W
logic control.
And the other problem is torch mode switch to strobe mode needs ramp
time because strobe and torch mode can't be co-exist.

> > >+MODULE_AUTHOR("Gene Chen <gene_chen@richtek.com>");
> > >+MODULE_DESCRIPTION("MT6360 Led Driver");
>
> Led -> LED.
>

ACK

>                                                                         P=
avel
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/b=
log.html