From: Marek Vasut <marex@denx.de>
To: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: Francesco Dolcini <francesco@dolcini.it>,
Richard Weinberger <richard@nod.at>,
Vignesh Raghavendra <vigneshr@ti.com>,
linux-mtd@lists.infradead.org,
Francesco Dolcini <francesco.dolcini@toradex.com>,
Shawn Guo <shawnguo@kernel.org>,
linux-arm-kernel@lists.infradead.org, stable@vger.kernel.org,
u-boot@lists.denx.de
Subject: Re: [PATCH v1] mtd: parsers: ofpart: Fix parsing when size-cells is 0
Date: Fri, 2 Dec 2022 17:17:59 +0100 [thread overview]
Message-ID: <0503c46d-c385-74f5-f762-51d87a5ebaff@denx.de> (raw)
In-Reply-To: <20221202164904.08d750df@xps-13>
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@denx.de 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?)
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next prev parent reply other threads:[~2022-12-02 16:19 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-02 7:19 [PATCH v1] mtd: parsers: ofpart: Fix parsing when size-cells is 0 Francesco Dolcini
2022-12-02 9:14 ` Miquel Raynal
2022-12-02 10:12 ` Francesco Dolcini
2022-12-02 10:24 ` Francesco Dolcini
2022-12-02 10:53 ` Miquel Raynal
2022-12-02 11:23 ` Francesco Dolcini
2022-12-02 14:05 ` Miquel Raynal
2022-12-02 14:31 ` Marek Vasut
2022-12-02 15:00 ` Miquel Raynal
2022-12-02 15:23 ` Marek Vasut
2022-12-02 15:49 ` Miquel Raynal
2022-12-02 16:01 ` Miquel Raynal
2022-12-02 16:17 ` Marek Vasut [this message]
2022-12-02 16:42 ` Miquel Raynal
2022-12-02 16:52 ` Marek Vasut
2022-12-02 16:57 ` Miquel Raynal
2022-12-02 17:08 ` Marek Vasut
2022-12-05 11:26 ` Francesco Dolcini
2022-12-05 13:49 ` Miquel Raynal
2022-12-05 16:25 ` Marek Vasut
2022-12-15 7:16 ` Miquel Raynal
2022-12-15 7:45 ` Marek Vasut
2022-12-15 8:04 ` Miquel Raynal
2022-12-16 0:36 ` Marek Vasut
2022-12-16 7:52 ` Francesco Dolcini
2022-12-16 7:45 ` Francesco Dolcini
2022-12-16 10:46 ` Marek Vasut
2022-12-16 11:01 ` Miquel Raynal
2022-12-16 12:37 ` Francesco Dolcini
2022-12-16 13:37 ` Miquel Raynal
2022-12-16 14:32 ` Marek Vasut
2022-12-16 15:35 ` Miquel Raynal
2022-12-16 16:30 ` Francesco Dolcini
2023-01-02 9:40 ` Miquel Raynal
2023-01-05 11:33 ` Miquel Raynal
2023-01-05 12:47 ` Francesco Dolcini
2023-01-05 14:51 ` Marek Vasut
2023-01-05 15:03 ` Miquel Raynal
2022-12-02 17:20 ` Francesco Dolcini
2022-12-05 11:30 ` Francesco Dolcini
2022-12-05 15:28 ` Miquel Raynal
2022-12-02 16:45 ` Francesco Dolcini
2022-12-02 17:05 ` Miquel Raynal
2022-12-02 15:56 ` Thorsten Leemhuis
2022-12-04 12:50 ` Marek Vasut
2022-12-04 12:59 ` Thorsten Leemhuis
2022-12-04 15:50 ` Marek Vasut
2022-12-02 12:43 ` Greg KH
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