Re: [PATCH V2 1/2] nvmem: core: refactor .cell_post_process() CB arguments

From: Michael Walle <michael@walle.cc>
To: "Rafał Miłecki" <zajec5@gmail.com>
Cc: "Srinivas Kandagatla" <srinivas.kandagatla@linaro.org>,
	"Miquel Raynal" <miquel.raynal@bootlin.com>,
	"Richard Weinberger" <richard@nod.at>,
	"Vignesh Raghavendra" <vigneshr@ti.com>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Krzysztof Kozlowski" <krzysztof.kozlowski+dt@linaro.org>,
	"Shawn Guo" <shawnguo@kernel.org>,
	linux-mtd@lists.infradead.org, devicetree@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, u-boot@lists.denx.de,
	"Rafał Miłecki" <rafal@milecki.pl>
Subject: Re: [PATCH V2 1/2] nvmem: core: refactor .cell_post_process() CB arguments
Date: Mon, 28 Nov 2022 08:35:24 +0100	[thread overview]
Message-ID: <f2bb569404903bc937fbe3840582f3c4@walle.cc> (raw)
In-Reply-To: <20221128065923.1180-1-zajec5@gmail.com>

Am 2022-11-28 07:59, schrieb Rafał Miłecki:
> From: Rafał Miłecki <rafal@milecki.pl>
> 
> Pass whole NVMEM cell struct and length pointer as arguments to 
> callback
> functions.
> 
> This allows:
> 
> 1. Cells content to be modified based on more info
>    Some cells (identified by their names) contain specific data that
>    needs further processing. This can be e.g. MAC address stored in an
>    ASCII format. NVMEM consumers expect MAC to be read in a binary 
> form.
>    More complex cells may be additionally described in DT. This change
>    allows also accessing relevant DT nodes and reading extra info.
> 
> 2. Adjusting data length
>    If cell processing results in reformatting it, it's required to
>    adjust length. This again applies e.g. to the MAC format change from
>    ASCII to the byte-based.
> 
> Later on we may consider more cleanups & features like:
> 1. Dropping "const char *id" and just using NVMEM cell name
> 2. Adding extra argument for cells providing multiple values
> 
> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
> ---
> This solution conflicts with 1 part of Michael's work:
> [PATCH v2 00/20] nvmem: core: introduce NVMEM layouts
> https://lore.kernel.org/linux-arm-kernel/20220901221857.2600340-1-michael@walle.cc/
> 
> Instead of:
> 1. Adding NVMEM cell-level post_process callback
> 2. Adding callback (.fixup_cell_info()) for setting callbacks
> 3. Dropping NVMEM device-level post_process callback
> I decided to refactor existing callback.
> 
> Michael's work on adding #nvmem-cell-cells should be possible to easily
> rebase on top of those changes.

As yours should be easily added on top of my series. I've showed that
providing a global post process hook is bad because that way you need
to have *all* cells of your device read-only.

-michael

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