linux-kernel - Re: [PATCH v2 3/3] dt-bindings: mtd: Document use of nvmem-partitions compatible

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 3 Mar 2021 11:01:55 +0100
From:   Rafał Miłecki <zajec5@...il.com>
To:     Ansuel Smith <ansuelsmth@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Richard Weinberger <richard@....at>
Cc:     devicetree@...r.kernel.org, Vignesh Raghavendra <vigneshr@...com>,
        Boris Brezillon <bbrezillon@...nel.org>,
        linux-kernel@...r.kernel.org, linux-mtd@...ts.infradead.org,
        Miquel Raynal <miquel.raynal@...tlin.com>
Subject: Re: [PATCH v2 3/3] dt-bindings: mtd: Document use of nvmem-partitions
 compatible

[Rob: please advise]

On 16.02.2021 22:26, Ansuel Smith wrote:
> Document nvmem-partitions compatible used to treat mtd partitions as a
> nvmem provider.

Until now we were using "compatible" string in partition node only for
parsers (looking for subpartitions). We need to think if this change can
break anything from DT / Linux perspective.

Compatible strings should be unique, so there is no risk of conflict
between NVMEM and parsers.

Now: can we ever need mtd partition to:
1. Contain subpartitions
2. Provide NVMEM
at the same time?

Let's say:

partition@0 {
	compatible = "vendor,dynamic-firmware-partitions", "nvmem-partitions";
	label = "firmware";
	reg = <0x0 0x100000>;
	#address-cells = <1>;
	#size-cells = <1>;
	ranges = <0 0x0 0x100000>;

	firmware-version@10 {
		reg = <0x10 0x4>;
	};

	firmware-date@10 {
		reg = <0x20 0x4>;
	};
};

Is that allowed to respect both "compatible" strings and have:
1. Linux parser parse "firmware" for subpartitions
2. Linux MTD register "firmware" as NVMEM device
?

If not, what other options do we have? Is that allowed to have a
dangling MTD NVMEM node with phandle to MTD partition?

firmware: partition@0 {
	compatible = "vendor,dynamic-firmware-partitions";
	label = "firmware";
	reg = <0x0 0x100000>;
};

(...)

firmware-version@10 {
	compatible = "mtd-nvmem";
	reg = <0x10 0x4>;
	mtd = <&firmware>;
};

firmware-date@10 {
	compatible = "mtd-nvmem";
	reg = <0x20 0x4>;
	mtd = <&firmware>;
};

Rob: I'd really appreciate your input & help here.