> -----Original Message----- > From: Philipp Zabel [mailto:[email protected]] > Sent: Thursday, January 22, 2015 11:38 PM > To: Shawn Guo > Cc: Cai Robby-R63905; [email protected]; Eric Nelson; Tim Harvey; > [email protected]; Troy Kisky; [email protected]; > [email protected]; [email protected]; linux-arm- > [email protected] > Subject: Re: [PATCH] ARM: dts: imx6qdl: Adjust the brightness setting for > LVDS panel > > Am Dienstag, den 20.01.2015, 19:38 +0800 schrieb Shawn Guo: > > Add LAKML and a few interested people. > > > > Shawn > > > > On Tue, Jan 20, 2015 at 06:22:35PM +0800, Robby Cai wrote: > > > Hannstar XGA panel is used by default on i.MX6QDL Sabre Auto/Lite/SD > > > or derived board. > > > > > > According to its data sheet [1], > > > a) the dimming duty cycle is 20% - 100%. > > > This patch changes the brightness-level from 20 to 100 with step 10 > > > to make it straight-forward. > > > b) the typical dimming frequency is 20KHz. > > > The previous setting is 200Hz. This patch corrects it. > > > > > > [1] > > > http://boundarydevices.com/wp-content/uploads/2013/06/HSD100PXN1-A00 > > > -C11-1.0.pdf > > > > > > Signed-off-by: Robby Cai <[email protected]> > > > --- > > > arch/arm/boot/dts/imx6qdl-gw52xx.dtsi | 6 +++--- > > > arch/arm/boot/dts/imx6qdl-gw53xx.dtsi | 6 +++--- > > > arch/arm/boot/dts/imx6qdl-gw54xx.dtsi | 6 +++--- > > > arch/arm/boot/dts/imx6qdl-nitrogen6x.dtsi | 6 +++--- > > > arch/arm/boot/dts/imx6qdl-sabreauto.dtsi | 6 +++--- > > > arch/arm/boot/dts/imx6qdl-sabrelite.dtsi | 6 +++--- > > > arch/arm/boot/dts/imx6qdl-sabresd.dtsi | 6 +++--- > > > 7 files changed, 21 insertions(+), 21 deletions(-) > > > > > > diff --git a/arch/arm/boot/dts/imx6qdl-gw52xx.dtsi > > > b/arch/arm/boot/dts/imx6qdl-gw52xx.dtsi > > > index b5756c2..33484d8 100644 > > > --- a/arch/arm/boot/dts/imx6qdl-gw52xx.dtsi > > > +++ b/arch/arm/boot/dts/imx6qdl-gw52xx.dtsi > > > @@ -29,9 +29,9 @@ > > > > > > backlight { > > > compatible = "pwm-backlight"; > > > - pwms = <&pwm4 0 5000000>; > > > - brightness-levels = <0 4 8 16 32 64 128 255>; > > > - default-brightness-level = <7>; > > > + pwms = <&pwm4 0 50000>; > > > + brightness-levels = <0 20 30 40 50 60 70 80 90 100>; > > > + default-brightness-level = <9>; > > I notice that the intervals are changed from exponential to linear. > Is this really wanted here? > I expect that the new settings result in huge steps in perceived > brightness at low levels and a nearly imperceptible change at the last > step. > > regards > Philipp
No particular reason here. I understand your concern but seems there's no obvious rule. How about add some interpolation, such as <0 52 64 96 128 160 192 224 255> or even more, <0 52 64 80 96 112 128 144 160 176 192 208 224 240 255> Regards, Robby
