On Thu, Nov 15, 2012 at 05:58:35PM +0900, Jingoo Han wrote:
> On Thursday, November 15, 2012 3:52 PM Thierry Reding wrote
> > On Thu, Nov 15, 2012 at 10:30:11AM +0900, Jingoo Han wrote:
> > > On Friday, November 09, 2012 11:05 PM Thierry Reding wrote
> > > >
> > > > This function finds the struct backlight_device for a given device tree
> > > > node. A dummy function is provided so that it safely compiles out if OF
> > > > support is disabled.
> > > >
> > > > Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxxxxxxxxxx>
> > >
> > > CC'ed Andrew Morton
> >
> > Yes, the backlight subsystem isn't very well maintained, so I should
> > have added Andrew in the first place. Thanks.
> >
> > >
> > > Hi Thierry Reding,
> > >
> > > The patch itself looks good.
> > > Could you explain when this API is used?
> > > Thank you.
> >
> > I use this for the upcoming Tegra DRM driver in order to hook up the
> > backlight with the DRM driver via DT to allow switching off the
> > backlight when the corresponding DRM output is switched of using DPMS.
> > Basically what you have is something like this in the device tree:
> >
> > display {
> > ...
> >
> > backlight = <&backlight>;
> >
> > ...
> > }
> >
> > Then you call something along these lines:
> >
> > np = of_parse_phandle(display, "backlight", 0);
> > if (np) {
> > backlight = of_find_backlight_by_node(np);
> > of_node_put(np);
> > }
> >
> > And then use the standard backlight API on the returned pointer.
>
> OK, I see how this API can be called.
> AS you mentioned, it will allow Tegra DRM driver to use
> the backlight driver.
>
> Acked-by: Jingoo Han <jg1.han@xxxxxxxxxxx>
Andrew,
any chance we could still get this in for the 3.8 merge window?
Thierry
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