From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Daniel Thompson <daniel.thompson@linaro.org>
Cc: ChiaEn Wu <peterwu.pub@gmail.com>,
Lee Jones <lee.jones@linaro.org>,
Jingoo Han <jingoohan1@gmail.com>, Pavel Machek <pavel@ucw.cz>,
Rob Herring <robh+dt@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Matthias Brugger <matthias.bgg@gmail.com>,
Sebastian Reichel <sre@kernel.org>,
Chunfeng Yun <chunfeng.yun@mediatek.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jonathan Cameron <jic23@kernel.org>,
Lars-Peter Clausen <lars@metafoo.de>,
Liam Girdwood <lgirdwood@gmail.com>,
Mark Brown <broonie@kernel.org>,
Guenter Roeck <linux@roeck-us.net>,
"Krogerus, Heikki" <heikki.krogerus@linux.intel.com>,
Helge Deller <deller@gmx.de>, ChiaEn Wu <chiaen_wu@richtek.com>,
Alice Chen <alice_chen@richtek.com>,
cy_huang <cy_huang@richtek.com>,
dri-devel <dri-devel@lists.freedesktop.org>,
Linux LED Subsystem <linux-leds@vger.kernel.org>,
devicetree <devicetree@vger.kernel.org>,
linux-arm Mailing List <linux-arm-kernel@lists.infradead.org>,
"moderated list:ARM/Mediatek SoC support"
<linux-mediatek@lists.infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux PM <linux-pm@vger.kernel.org>,
USB <linux-usb@vger.kernel.org>,
linux-iio <linux-iio@vger.kernel.org>,
"open list:FRAMEBUFFER LAYER" <linux-fbdev@vger.kernel.org>,
szuni chen <szunichen@gmail.com>
Subject: Re: [PATCH v4 13/13] video: backlight: mt6370: Add Mediatek MT6370 support
Date: Thu, 14 Jul 2022 11:49:30 +0200 [thread overview]
Message-ID: <CAHp75VdVSvux3HRPOj=xWXZoBdn1e=nSmWi9+BZUX69XAPcZPg@mail.gmail.com> (raw)
In-Reply-To: <20220714094709.6ekfnfcf5sktiegi@maple.lan>
On Thu, Jul 14, 2022 at 11:47 AM Daniel Thompson
<daniel.thompson@linaro.org> wrote:
>
> On Thu, Jul 14, 2022 at 11:27:07AM +0200, Andy Shevchenko wrote:
> > On Thu, Jul 14, 2022 at 9:13 AM ChiaEn Wu <peterwu.pub@gmail.com> wrote:
> > > I have tried two methods so far, as follows
> > > -------------------------------------------------------------
> > > /*
> > > * prop_val = 1 --> 1 steps --> b'00
> > > * prop_val = 2 ~ 4 --> 4 steps --> b'01
> > > * prop_val = 5 ~ 16 --> 16 steps --> b'10
> > > * prop_val = 17 ~ 64 --> 64 steps --> b'11
> > > */
> >
> > So, for 1 --> 0, for 2 --> 1, for 5 --> 2, and for 17 --> 3.
> > Now, consider x - 1:
> > 0 ( 0 ) --> 0
> > 1 (2^0) --> 1
> > 4 (2^2) --> 2
> > 16 (2^4) --> 3
> > 64 (2^6) --> ? (but let's consider that the range has been checked already)
> >
> > Since we take the lower limit, it means ffs():
> >
> > y = (ffs(x - 1) + 1) / 2;
> >
> > Does it work for you?
>
> To be honest, for this tiny table, writing code that *doesn't* require intricate
> deciphering together with a huge comment saying what is does would probably be
> better:
>
> prop_val = (prop_val <= 1 ? 0 :
> prop_val <= 4 ? 1 :
> prop_val <= 16 ? 2 :
> 3);
>
> This would be "obviously correct" and require no comment.
Agree. It will also limit checking (and whatever needed for that).
--
With Best Regards,
Andy Shevchenko
prev parent reply other threads:[~2022-07-14 9:50 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-04 5:38 [PATCH v4 00/13] Add Mediatek MT6370 PMIC support ChiaEn Wu
2022-07-04 5:38 ` [PATCH v4 01/13] dt-bindings: usb: Add Mediatek MT6370 TCPC ChiaEn Wu
2022-07-04 5:38 ` [PATCH v4 02/13] dt-bindings: power: supply: Add Mediatek MT6370 Charger ChiaEn Wu
2022-07-04 9:04 ` Krzysztof Kozlowski
2022-07-04 5:38 ` [PATCH v4 03/13] dt-bindings: leds: mt6370: Add Mediatek mt6370 current sink type LED indicator ChiaEn Wu
2022-07-04 5:38 ` [PATCH v4 04/13] dt-bindings: leds: Add Mediatek MT6370 flashlight ChiaEn Wu
2022-07-04 5:38 ` [PATCH v4 05/13] dt-bindings: backlight: Add Mediatek MT6370 backlight ChiaEn Wu
2022-07-04 5:38 ` [PATCH v4 06/13] dt-bindings: mfd: Add Mediatek MT6370 ChiaEn Wu
2022-07-04 9:07 ` Krzysztof Kozlowski
2022-07-04 5:38 ` [PATCH v4 07/13] mfd: mt6370: Add Mediatek MT6370 support ChiaEn Wu
2022-07-04 20:29 ` Andy Shevchenko
2022-07-04 5:38 ` [PATCH v4 08/13] usb: typec: tcpci_mt6370: Add Mediatek MT6370 tcpci driver ChiaEn Wu
2022-07-04 7:32 ` Greg KH
2022-07-04 9:31 ` szuni chen
2022-07-04 11:07 ` Greg KH
2022-07-04 20:19 ` Andy Shevchenko
2022-07-04 5:38 ` [PATCH v4 09/13] iio: adc: mt6370: Add Mediatek MT6370 support ChiaEn Wu
2022-07-04 20:35 ` Andy Shevchenko
2022-07-04 5:38 ` [PATCH v4 10/13] power: supply: mt6370: Add Mediatek MT6370 charger driver ChiaEn Wu
2022-07-04 20:53 ` Andy Shevchenko
2022-07-04 5:38 ` [PATCH v4 11/13] leds: mt6370: Add Mediatek MT6370 current sink type LED Indicator support ChiaEn Wu
2022-07-04 5:39 ` [PATCH v4 12/13] leds: flashlight: mt6370: Add Mediatek MT6370 flashlight support ChiaEn Wu
2022-07-04 21:05 ` Andy Shevchenko
2022-07-07 10:49 ` szuni chen
2022-07-04 5:39 ` [PATCH v4 13/13] video: backlight: mt6370: Add Mediatek MT6370 support ChiaEn Wu
2022-07-04 21:14 ` Andy Shevchenko
2022-07-13 10:53 ` ChiaEn Wu
2022-07-13 12:07 ` Andy Shevchenko
2022-07-13 13:07 ` Lee Jones
2022-07-14 7:13 ` ChiaEn Wu
2022-07-14 9:27 ` Andy Shevchenko
2022-07-14 9:43 ` Andy Shevchenko
2022-07-14 10:15 ` Andy Shevchenko
2022-07-14 9:47 ` Daniel Thompson
2022-07-14 9:49 ` Andy Shevchenko [this message]
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