Hi Marek, marex@xxxxxxx wrote on Fri, 2 Dec 2022 17:52:05 +0100: > On 12/2/22 17:42, Miquel Raynal wrote: > > Hi Marek, > > Hi, > > [...] > > >>> However, it should not be empty, at the very least a reg property > >>> should indicate on which CS it is wired, as expected there: > >>> https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git/tree/Documentation/devicetree/bindings/mtd/nand-chip.yaml?h=mtd/next > >> > >> OK, I see your point. So basically this? > >> > >> &gpmi { > >> #size-cells = <1>; > >> ... > >> nand-chip@0 { > >> reg = <0>; > >> }; > >> }; > >> > >> btw. the GPMI NAND controller supports only one chipselect, so the reg in nand-chip node makes little sense. > > > > I randomly opened a reference manual (IMX6DQL.pdf), they say: > > > > "Up to four NAND devices, supported by four chip-selects and one > > ganged ready/ busy." > > Doh, and MX7D has the same controller, so size-cells = <1>; makes sense with nand-chip@N {} . Actually #address-cells is here for that. You need to point at one CS, so in most cases this is: controller { #address-cells = <1>; #size-cells = <0>; chip@N { reg = <N>; }; }; > > > Anyway, the NAND controller generic bindings which require this reg > > property, what the controller or the driver actually supports, or even > > how it is used on current designs is not relevant here. > > > >>> But, as nand-chip.yaml references mtd.yaml, you can as well use > >>> whatever is described here: > >>> https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git/tree/Documentation/devicetree/bindings/mtd/mtd.yaml?h=mtd/next > >>> >>>> What would be the gpmi controller size cells (X) in that case, still 0, right ? So how does that help solve this problem, wouldn't U-Boot still populate the partitions directly under the gpmi node or into partitions sub-node ? > >>> > >>> The commit that was pointed in the original fix clearly stated that the > >>> NAND chip node was targeted > >> > >> I think this is another miscommunication here. The commit > >> > >> 753395ea1e45 ("ARM: dts: imx7: Fix NAND controller size-cells") > >> > >> modifies the size-cells of the NAND controller. The nand-chip is not involved in this at all . In the examples above, it's the "&gpmi" node size-cells that is modified. > > > > Yes I know. I was referring to this commit, sorry: > > 36fee2f7621e ("common: fdt_support: add support for "partitions" subnode to fdt_fixup_mtdparts()") > > > > The log says: > > > > Listing MTD partitions directly in the flash mode has been > > deprecated for a while for kernel Device Trees. Look for a node "partitions" in the > > found flash nodes and use it instead of the flash node itself for the > > partition list when it exists, so Device Trees following the current > > best practices can be fixed up. > > > > Which (I hope) means U-boot will equivalently try to play with the > > partitions container, either in the controller node or in the chip node. > > > >>> , not the NAND controller node. I hope this > >>> is correctly supported in U-Boot though. So if there is a NAND chip > >>> subnode, I suppose U-Boot would try to create the partitions that are > >>> inside, or even in the sub "partitions" container. > >> > >> My understanding is that U-Boot checks the nand-controller node size-cells, not the nand-chip{} or partitions{} subnode size-cells . > > > > I don't think U-Boot cares. > > > >> Francesco, can you please share the DT, including the U-Boot generated partitions, which is passed to Linux on Colibri MX7 ? I think that should make all confusion go away. > > > > Please also do it with the NAND chip described. If, when the NAND chip > > is described U-Boot tries to create partitions in the controller node, > > then the situation is even worse than I thought. But I believe > > describing the node like a suggest in the DT should prevent the boot > > failure while still allowing a rather good description of the hardware. > > > > BTW I still think the relevant action right now is to revert the DT > > patch. > > I am starting to bank toward that variant as well (thanks for clarifying the rationale in the discussion, that helped a lot). > > But then, the follow up fix would be what exactly, update the binding document to require #size-cells = <1>; ? Thanks, Miquèl
