linux-kernel - Re: [PATCH v2 1/3] mtd: partitions: ofpart: skip subnodes parse with compatible

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Message-ID: <d504a4df-b1f7-b7c9-e62a-599d114d8a18@gmail.com>
Date:   Tue, 2 Mar 2021 17:53:54 +0100
From:   Rafał Miłecki <zajec5@...il.com>
To:     Ansuel Smith <ansuelsmth@...il.com>,
        Richard Weinberger <richard@....at>
Cc:     devicetree@...r.kernel.org, Vignesh Raghavendra <vigneshr@...com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        linux-kernel@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
        linux-mtd@...ts.infradead.org,
        Miquel Raynal <miquel.raynal@...tlin.com>
Subject: Re: [PATCH v2 1/3] mtd: partitions: ofpart: skip subnodes parse with
 compatible

On 16.02.2021 22:26, Ansuel Smith wrote:
> If a partitions structure is not used, parse direct subnodes as
> fixed-partitions only if a compatible is not found or is of type
> fixed-partition. A parser can be used directly on the subnode and
> subnodes should not be parsed as fixed-partitions by default.
> 
> Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
> ---
>   drivers/mtd/parsers/ofpart.c | 5 +++++
>   1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/mtd/parsers/ofpart.c b/drivers/mtd/parsers/ofpart.c
> index daf507c123e6..4b363dd0311c 100644
> --- a/drivers/mtd/parsers/ofpart.c
> +++ b/drivers/mtd/parsers/ofpart.c
> @@ -50,6 +50,11 @@ static int parse_fixed_partitions(struct mtd_info *master,
>   			 master->name, mtd_node);
>   		ofpart_node = mtd_node;
>   		dedicated = false;
> +
> +		/* Skip parsing direct subnodes if a compatible is found and is not fixed-partitions */
> +		if (node_has_compatible(ofpart_node) &&
> +		    !of_device_is_compatible(ofpart_node, "fixed-partitions"))
> +			return 0;
>   	} else if (!of_device_is_compatible(ofpart_node, "fixed-partitions")) {
>   		/* The 'partitions' subnode might be used by another parser */
>   		return 0;

I admit I'm not familiar with the old binding, so let me know if my
understanding is incorrect.

It seems to me however that your change will break parsing in cases
like:

spi-flash@0 {
	compatible = "jedec,spi-nor";
	reg = <0x0>;

	partition@0 {
		label = "bootloader";
		reg = <0x0 0x100000>;
	};
};

nandcs@0 {
	compatible = "brcm,nandcs";
	reg = <0>;

	partition@0 {
		label = "bootloader";
		reg = <0x0000000 0x10000>;
	};
};

Did we ever use "fixed-partitions" without partitions { } subnode?