Re: [PATCH v1] mtd: parsers: ofpart: Fix parsing when size-cells is 0

From: Marek Vasut <marex@denx.de>
To: Francesco Dolcini <francesco@dolcini.it>,
	Miquel Raynal <miquel.raynal@bootlin.com>
Cc: 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: Thu, 5 Jan 2023 15:51:10 +0100	[thread overview]
Message-ID: <f689c22c-dd93-8143-c730-2af4d472bd0f@denx.de> (raw)
In-Reply-To: <Y7bG7GFDMS6bmQ4d@francesco-nb.int.toradex.com>

On 1/5/23 13:47, Francesco Dolcini wrote:
> Hello Miquel,

Hi,

[...]

>> Let's move forward with this. Let's assume my fears are baseless. We
>> might consider the situation where someone tries to hide the partitions
>> by setting #size-cell to 0 even wronger and too unlikely. Hopefully we
>> will not break any other existing setups by applying an always-on fix.
> 
> Nice, good!

Indeed

>> I would still like to see U-Boot partitions handling evolve, at least:
>> - fix #size-cells in fdt_fixup_mtd()
>> - avoid the fdt_fixup_mtd() call from Collibri boards (ie. an example
>>    that can be followed by the other users)
> 
> Fine, I can do it.
> 
> However I am just not 100% sure about your proposal, I wonder if we
> should just deprecate this function or we should fix it.

I would say fix it.

> The exact end result will depend on the discussion with the U-Boot
> folks, but I absolutely agree that the current situation needs to
> change. I'll keep you in CC on those patches.
> 
>> On Linux side let's fix #size-cells like you proposed without filtering
>> against a list of compatibles. We however need to improve the
>> heuristics:
>> - Do it only when there are partitions declared within a NAND
>>    controller node.
>> - Change the warning to avoid mentioning backward compatibility, just
>>    mention this is utterly wrong and thus the value will be set to 1
>>    instead of 0.
>> - Mention in the comment above this only works on systems with <4GiB
>>    chips.
>> If you think about other conditions please feel free to add them.
>>
>> Do you concur?
> Yes, I do agree.

Same here, agreed, thanks.

[...]

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