From: Stephen Warren <swarren@wwwdotorg.org>
To: "Philip, Avinash" <avinashphilip@ti.com>
Cc: grant.likely@secretlab.ca, rob.herring@calxeda.com,
rob@landley.net, rpurdie@rpsys.net,
thierry.reding@avionic-design.de,
broonie@opensource.wolfsonmicro.com, shawn.guo@linaro.org,
devicetree-discuss@lists.ozlabs.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org, nsekhar@ti.com,
gururaja.hebbar@ti.com
Subject: Re: [PATCH v2] pwm_backlight: Add device tree support for Low Threshold Brightness
Date: Thu, 20 Sep 2012 23:16:45 -0600 [thread overview]
Message-ID: <505BF83D.8040201@wwwdotorg.org> (raw)
In-Reply-To: <1348203080-16348-1-git-send-email-avinashphilip@ti.com>
On 09/20/2012 10:51 PM, Philip, Avinash wrote:
> Some backlights perform poorly when driven by a PWM with a short
> duty-cycle. For such devices, the low threshold can be used to specify a
> lower bound for the duty-cycle and should be chosen to exclude the
> problematic range.
>
> This patch adds support for an optional low-threshold-brightness
> property.
> diff --git a/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt b/Documentation/devicetree/bindings/video/backlight/pwm-backlight.txt
> Optional properties:
> - pwm-names: a list of names for the PWM devices specified in the
> "pwms" property (see PWM binding[0])
> + - low-threshold-brightness: brightness threshold low level. Low threshold
> + brightness set to value so that backlight present on low end of
> + brightness.
For my education, why not just specify values above this value in the
brightness-levels array; how do those two interact? It seems like any
description of that is missing from the PWM documentation, and would be
good to have in the DT binding too.
next prev parent reply other threads:[~2012-09-21 5:16 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-21 4:51 [PATCH v2] pwm_backlight: Add device tree support for Low Threshold Brightness Philip, Avinash
2012-09-21 5:16 ` Stephen Warren [this message]
2012-09-21 6:03 ` Philip, Avinash
2012-09-21 17:43 ` Stephen Warren
2012-09-25 4:29 ` Philip, Avinash
2012-09-25 6:19 ` Stephen Warren
2012-09-26 4:35 ` Philip, Avinash
2012-09-26 15:27 ` Stephen Warren
2012-09-26 16:49 ` Thierry Reding
2012-09-27 9:24 ` Philip, Avinash
2012-09-27 9:47 ` Thierry Reding
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