Hi Rob,
On Wed, Oct 26, 2016 at 05:13:46PM -0500, Rob Herring wrote:
> On Thu, Oct 20, 2016 at 11:43:37AM +0800, Chen-Yu Tsai wrote:
> > Some rgb-to-vga bridges have an enable GPIO, either directly tied to
> > an enable pin on the bridge IC, or indirectly controlling a power
> > switch.
> >
> > Add support for it.
> >
> > Signed-off-by: Chen-Yu Tsai <wens@xxxxxxxx>
> > ---
> > .../bindings/display/bridge/dumb-vga-dac.txt | 2 ++
> > drivers/gpu/drm/bridge/dumb-vga-dac.c | 28 ++++++++++++++++++++++
> > 2 files changed, 30 insertions(+)
> >
> > diff --git a/Documentation/devicetree/bindings/display/bridge/dumb-vga-dac.txt b/Documentation/devicetree/bindings/display/bridge/dumb-vga-dac.txt
> > index 003bc246a270..d3484822bf77 100644
> > --- a/Documentation/devicetree/bindings/display/bridge/dumb-vga-dac.txt
> > +++ b/Documentation/devicetree/bindings/display/bridge/dumb-vga-dac.txt
> > @@ -16,6 +16,8 @@ graph bindings specified in Documentation/devicetree/bindings/graph.txt.
> > - Video port 0 for RGB input
> > - Video port 1 for VGA output
> >
> > +Optional properties:
> > +- enable-gpios: GPIO pin to enable or disable the bridge
>
> This should also define the active state.
>
> > +static void dumb_vga_enable(struct drm_bridge *bridge)
> > +{
> > + struct dumb_vga *vga = drm_bridge_to_dumb_vga(bridge);
> > +
> > + if (vga->enable_gpio)
> > + gpiod_set_value_cansleep(vga->enable_gpio, 1);
>
> So the driver should allow either active high or low.
You mean like having a enable-active-high property? Isn't that
redundant with the GPIO flags?
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com
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