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From: Tony Lindgren <tony@atomide.com>
To: Rob Herring <robh@kernel.org>
Cc: Jean-Jacques Hiblot <jjhiblot@ti.com>,
	jacek.anaszewski@gmail.com, pavel@ucw.cz, sre@kernel.org,
	mark.rutland@arm.com, lee.jones@linaro.org,
	daniel.thompson@linaro.org, dmurphy@ti.com,
	linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org,
	dri-devel@lists.freedesktop.org, tomi.valkeinen@ti.com,
	devicetree@vger.kernel.org
Subject: Re: [PATCH v10 5/6] dt-bindings: backlight: Add led-backlight binding
Date: Thu, 21 Nov 2019 10:22:28 -0800	[thread overview]
Message-ID: <20191121182228.GO43123@atomide.com> (raw)
In-Reply-To: <20191009193523.GA7094@bogus>

Hi,

* Rob Herring <robh@kernel.org> [700101 00:00]:
> On Wed, Oct 09, 2019 at 10:51:26AM +0200, Jean-Jacques Hiblot wrote:
> > Add DT binding for led-backlight.
...
> > new file mode 100644
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/leds/backlight/led-backlight.yaml
...

> > +  default-brightness:
> > +    $ref: /schemas/types.yaml#/definitions/uint32
> > +    description: Default brightness level on boot.
> 
> It's not clear that this is an index when 'brightness-levels' is present 
> and absolute level when not. I wonder if we've been consistent on that?

Yeah.. And should we use "default-brightness-level" here like we do
in the kernel now?

Sorry if I've missed some discussion on this before..

> > +      brightness-levels = <0 4 8 16 32 64 128 255>;

What we're using for droid4 with an earlier version of this
patch set for the brightness-levels is generated backwards
with:

$ for i in 0 1 2 3 4 5 6 7; do echo "255 - ${i} * (256 / 8)" | bc; done

This produces the following range that seem to behave nicely:

brightness-levels = <31 63 95 127 159 191 223 255>;

Of course depends on the backing hardware, this is with
leds_lm3532 on droid4. But I think also the current example
in the binding might be from Pavel also for droid4?

If so, you might want to update the range :)

Regards,

Tony


  reply	other threads:[~2019-11-21 18:22 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-09  8:51 [PATCH v10 0/6] Add a generic driver for LED-based backlight Jean-Jacques Hiblot
2019-10-09  8:51 ` [PATCH v10 1/6] leds: populate the device's of_node Jean-Jacques Hiblot
2019-10-09 10:52   ` Tomi Valkeinen
2019-10-09  8:51 ` [PATCH v10 2/6] leds: Add of_led_get() and led_put() Jean-Jacques Hiblot
2019-10-09  8:51 ` [PATCH v10 3/6] leds: Add managed API to get a LED from a device driver Jean-Jacques Hiblot
2019-10-09  8:51 ` [PATCH v10 4/6] dts-bindings: leds: Document the naming requirement for LED properties Jean-Jacques Hiblot
2019-10-09 19:26   ` Rob Herring
2019-10-10 10:31     ` Jean-Jacques Hiblot
2019-10-09  8:51 ` [PATCH v10 5/6] dt-bindings: backlight: Add led-backlight binding Jean-Jacques Hiblot
2019-10-09 19:35   ` Rob Herring
2019-11-21 18:22     ` Tony Lindgren [this message]
2019-10-09  8:51 ` [PATCH v10 6/6] backlight: add led-backlight driver Jean-Jacques Hiblot
2019-11-21 18:13   ` Tony Lindgren
2020-01-07 10:28     ` Lee Jones
2020-01-07 13:45       ` Pavel Machek
2020-01-07 14:33         ` Lee Jones

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