On Thu, Dec 10, 2015 at 10:21:27AM +0100, Geert Uytterhoeven wrote: > On Fri, Nov 20, 2015 at 4:33 PM, Laurent Pinchart > <laurent.pinchart@xxxxxxxxxxxxxxxx> wrote: > > On Friday 20 November 2015 16:30:22 Geert Uytterhoeven wrote: > >> On Fri, Nov 20, 2015 at 3:52 PM, Laurent Pinchart wrote: > >> > On Friday 20 November 2015 08:46:56 Geert Uytterhoeven wrote: > >> >> On Thu, Nov 19, 2015 at 9:55 PM, Laurent Pinchart wrote: > >> >>> On Thursday 19 November 2015 19:38:56 Geert Uytterhoeven wrote: > >> >>>> The "renesas,scif" compatible value is currently used for the SCIF > >> >>>> variant in all Renesas SoCs of the R-Car family. However, the variant > >> >>>> used in the R-Car family is not the common "SH-4(A)" variant, but a > >> >>>> derivative with added "Baud Rate Generator for External Clock" (BRG), > >> >>>> which is also present in sh7734. > >> >>> > >> >>> Time to introduce a "renesas,scif-rcar" compatible string ? ;-) > >> >>> > >> >>> As the only DT-enabled platform to have a different SCIF type is > >> >>> r7s72100 we could also consider just switching the regtype to > >> >>> SCIx_SH4_SCIF_BRG_REGTYPE for the generic "renesas,scif" entry as it's > >> >>> listed after the "renesas,scif- r7s72100" entry. That might cause an > >> >>> issue if we want to enable DT on arch/sh though, but even if that > >> >>> happens due to the J-Core processors I'd be surprised to see the old > >> >>> Renesas SH platforms being moved to DT. > >> >> > >> >> I thought about that, but you never know in which out-of-tree BSP it > >> >> ended up being used, too. So better safe than sorry. > >> > > >> > Out-of-tree should be banned :-) > >> > > >> > More seriously, I suppose you wouldn't be thrilled by the idea of a > >> > "renesas,scif-rcar-gen2" ? > >> > >> Nope. Note that it's also used in R-Car Gen 1 and Gen 3, and sh7734. > > > > Yes, but it would at least cover the whole Gen2 family that behaves the same > > way. And wouldn't preclude adding "renesas,scif-rcar-gen1". That's two compat > > strings only. > > In light of all the recent "add fallback compatibility strings" patch series > from Simon, perhaps I should reconsider, and just match against three (new) > family-specific compatible values: > > "renesas,scif-rcar-gen1" > "renesas,scif-rcar-gen2" > "renesas,scif-rcar-gen3" > > instead of the 8 (and more coming) SoC-specific compatible values? > > Following that scheme means we will have to add many compatible values > to the existing dtsis. I.e. every SCIx device node (there are more than 100) > will have 3, like > > scif0: serial@e6e60000 { > compatible = "renesas,scif-r8a7791", "renesas,scif-rcar-gen2", > "renesas,scif"; > > Not having the SoC-specific ones in the driver won't cause an issue when using > an old DTS with a new kernel: you can't use the new BRG features without > adding the extra clocks to the DTS anyway, so you can add the family-specific > compatible value when doing that update. > > Simon, what do you think? This sounds good to me. In fact it sounds like the kind of upgrade path that I would like to see in action. -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html