Re: [PATCH 11/11] ARM: versatile: move CLCD configuration to device tree

[Tomi Valkeinen <tomi.valkeinen@ti.com>]

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On 25/02/16 21:30, Linus Walleij wrote:
> On Thu, Feb 25, 2016 at 5:45 PM, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote:
>> On 25/02/16 16:04, Linus Walleij wrote:
> 
>>> *All* the others
>>> will be very happy with *ONE* display defined as panel in the
>>> device tree, and off they go. Usually VGA. And that will look
>>
>> You keep mentioning VGA. So is there are VGA output? Or do you just mean
>> MIPI DPI panels, which happen to take the same video timings as VGA?
> 
> Russell beat me to it, yes there is an external VGA encoder.
> It needs some bits set up through the "misc registers" system
> controller as indicated. From the CLCD hardware point of view
> it's no different than any other panel. So the DTS fragment looks
> like so:
> 
>                         panel {
>                                 compatible = "panel-dpi";
> 
>                                 port {
>                                         clcd_panel: endpoint {
>                                                 remote-endpoint = <&clcd_pads>;
>                                         };
>                                 };
> 
>                                 /* Standard 640x480 VGA timings */
>                                 panel-timing {
>                                         clock-frequency = <25175000>;
>                                         hactive = <640>;
>                                         hback-porch = <48>;
>                                         hfront-porch = <16>;
>                                         hsync-len = <96>;
>                                         vactive = <480>;
>                                         vback-porch = <33>;
>                                         vfront-porch = <10>;
>                                         vsync-len = <2>;
>                                 };
>                         };
> 
> 
> This is reported as the default display type if no LCD panel
> is connected.
> 
> If a LCD panel is also connected, it take precedence.

Ok. Well... It's all wrong, but I don't know how much time we want to
spend on fixing that.

Although one thing to consider is that if there is ever going to be a
DRM driver for CLCD, it would be good to have the device tree parts
correctly representing the hardware, so that the DRM driver could be
implemented in a cleaner, more generic way.

 Tomi


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