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>
Best regards,
Jingoo Han
>
> Thierry
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