linux-kernel - Re: [PATCH v4 0/4] Add a generic driver for LED-based backlight

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Date:   Mon, 22 Jul 2019 08:06:20 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     Jacek Anaszewski <jacek.anaszewski@...il.com>
Cc:     Jean-Jacques Hiblot <jjhiblot@...com>, pavel@....cz,
        robh+dt@...nel.org, mark.rutland@....com,
        daniel.thompson@...aro.org, jingoohan1@...il.com, dmurphy@...com,
        linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, tomi.valkeinen@...com
Subject: Re: [PATCH v4 0/4] Add a generic driver for LED-based backlight

On Thu, 18 Jul 2019, Jacek Anaszewski wrote:

> On 7/17/19 4:15 PM, Jean-Jacques Hiblot wrote:
> > This series aims to add a led-backlight driver, similar to pwm-backlight,
> > but using a LED class device underneath.
> > 
> > A few years ago (2015), Tomi Valkeinen posted a series implementing a
> > backlight driver on top of a LED device:
> > https://patchwork.kernel.org/patch/7293991/
> > https://patchwork.kernel.org/patch/7294001/
> > https://patchwork.kernel.org/patch/7293981/
> > 
> > The discussion stopped because Tomi lacked the time to work on it.
> > 
> > changes in v4:
> > - fix dev_err() messages and commit logs following the advices of Pavel
> > - cosmetic changes (indents, getting rid of  "? 1 : 0" in
> >   led_match_led_node())
> > 
> > changes in v3:
> > - dt binding: don't limit the brightness range to 0-255. Use the range of
> >   the underlying LEDs. as a side-effect, all LEDs must now have the same
> >   range
> > - driver: Adapt to dt binding update.
> > - driver: rework probe() for clarity and remove the remaining goto.
> > 
> > changes in v2:
> > - handle more than one LED.
> > - don't make the backlight device a child of the LED controller.
> > - make brightness-levels and default-brightness-level optional
> > - removed the option to use a GPIO enable.
> > - removed the option to use a regulator. It should be handled by the LED
> >   core
> > - don't make any change to the LED core (not needed anymore)
> > 
> > Jean-Jacques Hiblot (2):
> >   leds: Add managed API to get a LED from a device driver
> >   dt-bindings: backlight: Add led-backlight binding
> > 
> > Tomi Valkeinen (2):
> >   leds: Add of_led_get() and led_put()
> >   backlight: add led-backlight driver
> > 
> >  .../bindings/leds/backlight/led-backlight.txt |  28 ++
> >  drivers/leds/led-class.c                      |  92 ++++++
> >  drivers/video/backlight/Kconfig               |   7 +
> >  drivers/video/backlight/Makefile              |   1 +
> >  drivers/video/backlight/led_bl.c              | 268 ++++++++++++++++++
> >  include/linux/leds.h                          |   6 +
> >  6 files changed, 402 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/leds/backlight/led-backlight.txt
> >  create mode 100644 drivers/video/backlight/led_bl.c
> > 
> 
> For the whole set:
> 
> Acked-by: Jacek Anaszewski <jacek.anaszewski@...il.com>
> 
> Lee - we need to create immutable branch for this set since there will
> be some interfering changes in the LED core in this cycle.
> 
> I can create the branch and send the pull request once we will
> obtain the ack from Rob for DT bindings, unless you have other
> preference.

We also require a review to be conducted by Daniel Thompson.

After which, an immutable branch sounds like a good idea.  I'd like to
create this myself if you don't mind.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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