imx-drm: ldb and display power on sequence

[p.zabel@pengutronix.de (Philipp Zabel)]

Hi Christian,

Am Donnerstag, den 06.03.2014, 13:34 +0100 schrieb Christian Gmeiner:
> Hi all.
> 
> On our custom board design (imx6d) we are using a TFT-display
> connceted via LVDS.
> The datasheet [0] says that the display needs a defined power up
> sequence. I need
> to control the following stuff:
> 
> - LCD_ON (gpio2 3)
> - Backlight ON (gpio2 0)
> - PMW for dimm
> 
> At the moment I have the backlight suff ready:
> 
>        backlight {
>                compatible = "pwm-backlight";
>                pwms = <&pwm4 0 50000>;
>                enable-gpios = <&gpio2 0 0>;
> 
>                brightness-levels = <0 1 2 3 4>;
>                default-brightness-level = <4>;
>        };
> 
> Now I only need to enable the LCD_ON and wait 40ms before turning on
> the LVDS clocks and data.

This can be done by adding a regulator-enable-ramp-delay property to the
gpio regulator.

> For this I tought to add a regulator support in
> imx_ldb_encoder_commit(..) of imx-ldb.c.
>That should give me the correct sequence for
> LVDS on to LVDS data/clock. Now I only need to get the pwm-backlight
> driver doing its work after ldb is ready.

We should rather add drm_panel support to imx-ldb. I have just sent a
patch for this.
The simple-panel driver already supports regulator and backlight.

regards
Philipp