On Sat, 12 May 2018 11:38:26 -0300 Paul Cercueil <paul@xxxxxxxxxxxxxxx> wrote: > Le sam. 12 mai 2018 à 10:42, Boris Brezillon > <boris.brezillon@xxxxxxxxxxx> a écrit : > > On Sat, 12 May 2018 08:55:40 -0300 > > Paul Cercueil <paul@xxxxxxxxxxxxxxx> wrote: > > > >> Hi Boris, > >> > >> Le 12 mai 2018 02:55, Boris Brezillon <boris.brezillon@xxxxxxxxxxx> > >> a écrit : > >> > > >> > Hi Paul, > >> > > >> > On Fri, 11 May 2018 23:29:12 +0200 > >> > Paul Cercueil <paul@xxxxxxxxxxxxxxx> wrote: > >> > > >> > > By specifying the properties "mtd-oob-ecc" and "mtd-oob-free", > >> it is > >> > > now possible to specify from devicetree where the ECC data is > >> located > >> > > inside the OOB region. > >> > > >> > Why would we want to do that? I mean, ECC/free regions are ECC > >> > controller dependent (and NAND chip dependent for the OOB size > >> part), > >> > so there's no reason to describe it in the DT. And more > >> importantly, > >> > people are likely to get it wrong. > >> > > >> > I'm curious, why do you need that? > >> > >> Good question. > >> > >> The reason is that some SoCs have no ECC controller. > >> The various boards for these SoCs then all use a different layout. > > > > Okay. Still think defining the layouts in the DT is a bad idea. We > > can add a jz4740 specific property to define the layout id > > (ingenic,nand-oob-layout = <layout-id>), but not a generic way to > > define custom layouts for all kind of NAND controller. > > Okay. > > >> > >> My motivation is to get rid of this (move it to devicetree): > >> > >> https://elixir.bootlin.com/linux/latest/source/arch/mips/jz4740/board-qi_lb60.c#L93 > >> And enable the support of other boards with custom OOB layouts. > > > > Can you list the different layouts you have? I'm pretty sure there's a > > pattern. Maybe we can even deduce the layout from the page size or OOB > > size. > > This is the other layout I have for another ingenic device: > http://projects.qi-hardware.com/index.php/p/qi-kernel/source/tree/od-2011-09-18/arch/mips/jz4740/board-a320.c#L125 > > Page size and OOB size are the same between these two devices. Indeed. Do you know if there are other kind of layouts in the wild? Note that <layout-id> can be a string, so if each each board is defining its own layout, you could specify the board name here. Otherwise, if you just have those 2 patterns, you can just name them "contiguous" and "interleaved". -- 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
