* Javier Martinez Canillas <javier@xxxxxxxxxxxx> [140512 03:01]: > Hello Tomi, > > On Mon, May 12, 2014 at 11:40 AM, Tomi Valkeinen <tomi.valkeinen@xxxxxx> wrote: > > On 12/05/14 12:34, Javier Martinez Canillas wrote: > > > >> Maybe we can remove this hackery by relying on the fact that a > >> compatible string can have a set of values that goes from more > >> specific to more general. So you can have something like: > >> > >> compatible = "sony,panel-foobar", "omapdss,panel-foobar" > >> > >> So right now only "omapdss,panel-foobar" will be matched and later > >> when we have common panel drivers then that driver could handle the > >> "sony,panel-foobar" compatible string. > >> > >> Other platforms could do something similar and have > >> > >> compatible = "sony,panel-foobar", "baz,panel-foobar" > >> > >> That way you won't break DT backward compatible but still not require > >> hacks on arch/arm/mach-omap2/display.c. > >> > >> We do the same for OMAP boards, we now have the following compatible string: > >> > >> compatible = "isee,omap3-igep0020", "ti,omap36xx", "ti,omap3"; > >> > >> There isn't a struct machine_desc that matches "isee,omap3-igep0020" > >> but later if we find that we need some board specific initialization > >> we could add one without breaking existing DTS. In fact it used to be > >> a single machine_desc that matched "ti,omap3" for both omap36xx and > >> omap34xx but later when some DT clocks changes were introduced we > >> needed to split both SoC families. > > > > I think that's a different thing. "isee,omap3-igep0020" is a proper > > compatible string, if the board is "isee,...". No matter what software > > you run, that's correct and fine. > > > > The omapdss case is different, there the "omapdss" points to a sw thing, > > it does not describe the hardware. It's only needed as we don't have > > proper sw drivers for the devices. > > > > That said, I think what you describe would work. But I would rather keep > > the .dts files clean and correct, and keep that hacks hidden inside the > > kernel. > > > > Thanks for the explanation. Since DT are meant to describe hardware > and not software I agree with you that we shouldn't leak an > implementation detail to the DeviceTrees. > > And after all fortunately we don't have a stable API in the kernel > like the one that is enforced in the DT so we can fix it later ;-) This remapping of compatible flags sounds smelly to me, please discuss it first with the device tree people. I think we're better off just using the compatible properties limited to the simple-panel.txt for now and actually describe the real hardware. The fact that the panel is connected to DSS should be possible to find out based on the phandles. Regards, Tony -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
