[Gta04-owner] Linux 3.2-rc3 on GTA04

NeilBrown neilb at suse.de
Sun Nov 27 04:57:16 CET 2011


On Sun, 27 Nov 2011 01:19:18 +0100 Christoph Mair <christoph.mair at gmail.com>
wrote:

> On Sat, Nov 26, 2011 at 12:43 PM, NeilBrown <neilb at suse.de> wrote:
> 
> >  - Brand new driver for the LEDs (tca6507] [2]
> >  - Backlight control with PWM - untested [3]
> 
> >  2/ My new from-scratch driver for leds-tca6507 provides full support for
> >    setting brightness levels and hardware-assisted blinking, all through the
> >    standard /sys/class/leds/* interface.  The leds are given names:
> >       gta04:{red,green}:{aux,power}
> >    (no blue LED - I'm sad :-)
> This works fine, also with triggers (for charging and SD access).
> 
> >    The driver can also make lines appear as GPIO output.  The Wifi reset now
> >    appears as /sys/class/gpio/WiFi-Reset
> >    (I haven't tested it though).
> 
> 
> >  3/ I included the PWM (Pulse Width Modulation) driver that Nikolaus mentions
> >    in http://projects.goldelico.com/p/gta04-kernel/issues/85/ and figured
> >    out how to link it up with the backlight function.
> >
> >    I've checked that 'setterm -blank force' and 'setterm -blank poke' cause
> >    the PWM module to request different pulse widths, but I don't know if
> >    it is actually affecting the backlight (because I don't have one plugged
> >    in).
> >    Test reports would be most welcome.
> 
> Changing the brightness using
> /sys/class/backlight/pwm-backlight/brightness works great. Values
> between 12 and 100 do enable and dim the backlight. With values <= 11
> the display stays dark.
>

That's excellent - thanks.

I assume this appears as a step-change and not just that it becomes too dim
for you to see?
Maybe it would be worth encoding this as the 'lth' value.... I wonder what
'lth' is short for..

diff --git a/arch/arm/mach-omap2/board-omap3gta04.c b/arch/arm/mach-omap2/board-omap3gta04.c
index d9f79da..b953ca0 100644
--- a/arch/arm/mach-omap2/board-omap3gta04.c
+++ b/arch/arm/mach-omap2/board-omap3gta04.c
@@ -237,6 +237,7 @@ static struct platform_pwm_backlight_data pwm_backlight = {
 	.max_brightness = 100,
 	.dft_brightness = 100,
 	.pwm_period_ns  = 2000000, /* 500 Hz */
+	.lth_brightness = 11, /* Below 11% display appears as off */
 };
 static struct platform_device backlight_device = {
 	.name = "pwm-backlight",

NeilBrown
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