On 31.05.2018 22:30, Boris Brezillon wrote: > On Thu, 31 May 2018 19:54:08 +0200 > Stefan Agner <stefan@xxxxxxxx> wrote: > >> >> + >> >> + mtd->dev.parent = &pdev->dev; >> >> + mtd->name = "tegra_nand"; >> > >> > I just figured it was undocumented (yet) but you could have a label >> > string property in your nand DT node that tells you the name of the >> > MTD device instead of something too generic like tegra_nand. >> > >> >> Using label in the NAND chip subnode actually causes current U-Boot to >> delete (!!) the chip node and create partitions on the controller node. >> >> See: >> https://elixir.bootlin.com/u-boot/latest/source/common/fdt_support.c#L757 >> >> The code essentially uses the property label to detect whether its a >> NAND chip or a partition... > > Why not fixing that in uboot? The representation where the NAND device > and NAND controller are mixed in a single node called nand@xxx is just > wrong from a HW PoV, and it seems uboot is using this representation, > which is probably why you have a problem when trying to find the > partition directly under the NAND controller node. > >> >> At least this is the case when using fdt_fixup_mtdparts and passing the >> controller compatible ("nvidia,tegra20-nand") in node_info, > > Just a digression, but I recommend using > "nvidia,tegra20-nand-controller" for the compatible, because the node > is describing the NAND controller not the NAND chip. > Ok. >> what our >> downstream U-Boot is currently doing. Maybe we should pass the >> compatible property of the NAND chip? > > Or maybe you should search for partitions in children of the controller > node instead of searching directly under the controller node itself. > Yes, that is what it is doing... But only if that child has not a label. fdt_fixup_mtdparts is common code. Change the behaviour now probably breaks boards... Anyway, this discussion needs to be shifted to the U-Boot mailing list. >> But afaik, chips do not have a >> compatible necessarily. > > Nope, and it should stay like that. > >> >> So using label in the chip node is currently a no-go for me. > > I hope I'm wrong but I fear this is not the only problem you'll face > when switching to a controller+chip representation. This is just the > tip of the iceberg. > Works not too bad otherwise, so far :-) >> >> Will send out v3 soon. > > Sure, let's see how v3 looks. -- Stefan -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
