[RFC][PATCH] regulator: rpi-panel: Add regulator/backlight driver for RPi panel

[Marek Vasut]

On 7/30/20 5:59 PM, Sam Ravnborg wrote:
> Hi Marek

Hi,

> On Wed, Jul 29, 2020 at 11:46:45PM +0200, Marek Vasut wrote:
>> This regulator/backlight driver handles the ATTINY88 present on the
>> RPi 7" touchscreen panel and exposes the power/backlight interfaces.
[...]
> It looks strange that the regulator and the backligth are defined in the
> same module like this.

It's one chip, attiny with custom firmware, what do you want me to do
about it ? I can over-complicate this and split it into multiple
drivers, but I don't think it's worth the complexity, considering that
this is likely a one-off device which will never be re-used elsewhere,
except on this one particular display module for RPi.

> The usual approach is to have an independent regulator and an
> independent backlight. Each are represented by their own node in the DT.
> 
> Also the compatible "raspberrypi,7inch-touchscreen-panel-regulator",
> is unknown. We need a binding for the compatible.

I submitted the patch as RFC to get feedback on how to handle this, so
yes, there are no DT bindings, that's on the todo.

> For backlight drivers, and modules that includes backlight support it
> would be good to include the backlight gang in cc:
> Jingoo, Lee, Daniel.

[...]