Re: [PATCH RFC 1/2] dt-bindings: simplefb: Support a list of regulator supply properties

[Hans de Goede]

Hi,

On 13-10-15 04:22, Chen-Yu Tsai wrote:
> On Tue, Oct 13, 2015 at 1:10 AM, Mark Rutland <mark.rutland@xxxxxxx> wrote:
> > On Tue, Oct 13, 2015 at 01:04:17AM +0800, Chen-Yu Tsai wrote:
> > > The physical display tied to the framebuffer may have regulators
> > > providing power to it, such as power for LCDs or interface conversion
> > > chips.
> > >
> > > The number of regulators in use may vary, but the regulator supply
> > > binding can not be a list. Work around this by adding a "num-supplies"
> > > property to communicate the number of supplies, and a list of 0 ~ N
> > > "vinN-supply" properties for the actual regulator supply.
> >
> > This is getting more complicated by the minute...
>
> Yeah...
>
> I considered "backlight" and "panel" properties, but that seems to need
> more effort to parse. Regulators seemed easier.
>
> > > Signed-off-by: Chen-Yu Tsai <wens@xxxxxxxx>
> > > ---
> > >   .../devicetree/bindings/video/simple-framebuffer.txt       | 14 ++++++++++----
> > >   1 file changed, 10 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/Documentation/devicetree/bindings/video/simple-framebuffer.txt b/Documentation/devicetree/bindings/video/simple-framebuffer.txt
> > > index 4474ef6e0b95..0cc43e1be8b5 100644
> > > --- a/Documentation/devicetree/bindings/video/simple-framebuffer.txt
> > > +++ b/Documentation/devicetree/bindings/video/simple-framebuffer.txt
> > > @@ -47,10 +47,14 @@ Required properties:
> > >     - a8b8g8r8 (32-bit pixels, d[31:24]=a, d[23:16]=b, d[15:8]=g, d[7:0]=r).
> > >
> > >   Optional properties:
> > > -- clocks : List of clocks used by the framebuffer. Clocks listed here
> > > -           are expected to already be configured correctly. The OS must
> > > -           ensure these clocks are not modified or disabled while the
> > > -           simple framebuffer remains active.
> > > +- clocks : List of clocks used by the framebuffer.
> > > +- num-supplies : The number of regulators used by the framebuffer.
> > > +- vinN-supply : The N-th (from 0) regulator used by the framebuffer.
> >
> > I don't see why you need num-supplies. Why not just try probing
> > vin${N}-supply until such a property isn't present in the DT?

+1 for this.

> That's doable. Though I'd add a hard limit on it. Does 16 seem reasonable?

I would not add a hard limit to the binding, you can use a fixed array in
the code to make the code simpler. I would say 8 should be sufficient, since
the limit will only be in the code we can always bump it when we need to.

Regards,

Hans
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