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

[Linus Walleij]

On Wed, Feb 17, 2016 at 10:09 AM, Tomi Valkeinen <tomi.valkeinen at ti.com> wrote:

>> Tested on Versatile AB with just VGA with the default device tree,
>> and with the IB2 daughterboard with the custom IB2 device tree.
>> Tested to shunt in XVGA by modifying the device tree and this works
>> too. Also tested on QEMU for Versatile in both VGA and Sanyo 2.5"
>> mode. I don't have the IB1 daughterboard and its add-on displays,
>> but it should work as long as the detection mechanism and device
>> tree parameters are sound.
>
> Well... I don't like this very much. The .dts should contain
> descriptions for hardware that is connected. Have you looked at DT
> overlays? I think they would be a much better match for this.

I'll look into it. I don't know how good those are. They must be overlaid
at runtime and anyways exist somewhere in memory so they can be
overlaid in there.

> What's the SYS_CLCD register? An EEPROM or such, programmed when the
> board is manufactured? Is the panel meant to be switchable by the user,
> possibly to a panel that's not "standard"?

As Russell points out: it's a register that contains a number saying what
panel is connected.

So it is plug-n-play and I want to preserve this in the patch.

The alternative is to make one DTS per display type connected, but that is
loosing all the nice plug'n'play :(

But if an overlay can do the same, I'm game for it.

Yours,
Linus Walleij