On 12/2/22 16:49, Miquel Raynal wrote:
Hi Marek,
Hi,
On 12/2/22 16:00, Miquel Raynal wrote:
Hi Marek,
Hi,
marex@xxxxxxx wrote on Fri, 2 Dec 2022 15:31:40 +0100:
On 12/2/22 15:05, Miquel Raynal wrote:
Hi Francesco,
Hi,
[...]
I still strongly disagree with the initial proposal but what I think we
can do is:
1. To prevent future breakages:
Fix fdt_fixup_mtdparts() in u-boot. This way newer U-Boot + any
kernel should work.
2. To help tracking down situations like that:
Keep the warning in ofpart.c but continue to fail.
3. To fix the current situation:
Immediately revert commit (and prevent it from being backported):
753395ea1e45 ("ARM: dts: imx7: Fix NAND controller size-cells")
This way your own boot flow is fixed in the short term.
Here I disagree, the fix is correct and I think we shouldn't
proliferate incorrect DTs which don't match the binding document.
I agree we should not proliferate incorrect DTs, so let's use a modern
description then
Yes please !
, with a controller and a child node which defines the
chip.
But what if there is no chip connected to the controller node ?
If I understand the proposal here right (please correct me if I'm wrong), then:
Good idea to summarize.
1) This is the original, old, wrong binding:
&gpmi {
#size-cells = <1>;
...
partition@N { ... };
};
Yes.
2) This is the newer, but still wrong binding:
&gpmi {
#size-cells = <0>;
...
partitions {
partition@N { ... };
};
};
Well, this is wrong description, but it would work (for compat reasons,
even though I don't think this is considered valid DT by the schemas).
3) This is the newest binding, what we want:
&gpmi {
#size-cells = <0>;
...
nand-chip {
partitions {
partition@N { ... };
};
};
};
Yes
But if there is no physical nand chip connected to the controller, would we end up with empty nand-chip node in DT, like this?
&gpmi {
#size-cells = <X>;
...
nand-chip { /* empty */ };
};
Is this really a concern?
I don't know, maybe it is not.
If there is no NAND chip, the controller
should be disabled, no? I guess technically you could even use the
status property in the nand-chip node...
Sure.
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.
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.
, 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 .
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.
(or am I the only one who's still confused here?)
