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Message-ID: <20190724082253.GA23552@amd>
Date: Wed, 24 Jul 2019 10:22:53 +0200
From: Pavel Machek <pavel@....cz>
To: Dan Murphy <dmurphy@...com>
Cc: linux-omap@...r.kernel.org, tony@...mide.com, sre@...nel.org,
nekit1000@...il.com, mpartap@....net, merlijn@...zup.org,
jacek.anaszewski@...il.com, linux-kernel@...r.kernel.org,
linux-leds@...r.kernel.org
Subject: Re: Backlight in motorola Droid 4
On Tue 2019-07-23 10:53:16, Dan Murphy wrote:
> Pavel
>
> On 7/22/19 3:59 PM, Pavel Machek wrote:
> >Hi!
> >
> >So now the backlight LED can be controlled. Good. (And thanks!)
> >
> >But I seem to remember that backlight had range from "is it really on?"
> >to "very bright"; now it seems to have range from "bright" to "very
> >bright".
> >
> >Any ideas what goes on there?
>
> In the LM3552 driver we are changing the Full scale brightness registers for
> the
>
> specific control bank.
>
> #define LM3532_REG_CTRL_A_BRT 0x17
> #define LM3532_REG_CTRL_B_BRT 0x19
> #define LM3532_REG_CTRL_C_BRT 0x1b
Yep, and those registers are 5-bit linear...
> In the ti-lmu code the ALS zones were being modified not the control bank
> brightness.
>
> #define LM3532_REG_BRT_A 0x70 /* zone 0 */
> #define LM3532_REG_BRT_B 0x76 /* zone 1 */
> #define LM3532_REG_BRT_C 0x7C /* zone 2 */
...while these allow 14-bits of control.
That explains very limited range of backlight control.
Do you have any plans to change that?
Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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