linux-kernel - Re: [PATCH 1/2] mtd: add support for partition parsers

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Date:   Sat, 17 Sep 2016 12:00:22 +0200
From:   Richard Weinberger <richard.weinberger@...il.com>
To:     Rafał Miłecki <zajec5@...il.com>
Cc:     Brian Norris <computersforpeace@...il.com>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        David Woodhouse <dwmw2@...radead.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] mtd: add support for partition parsers

Rafał,

On Tue, Jul 19, 2016 at 10:51 PM, Rafał Miłecki <zajec5@...il.com> wrote:
> This extends MTD subsystem by adding a support for partition parsers
> that should be used for creating subpartitions. There are some types of
> partitions that require splitting, like firmware containers.
> It's common some home routers that a single firmware image gets flashed
> to predefined partition and then we need to parse it dynamically.
>
> The reason for having such parsers is to share code. Right now we have
> e.g. TRX parsing implemented in bcm47xxpart but this could be used in
> more cases (e.g. on ramips which doesn't use bcm47xxpart or with DT).
>
> This implementation requires marking partition as requiring parsing with
> a specific parser. This can be used right away with some parsers like
> bcm47xxpart, in future we will hopefully also find a solution for doing
> it with ofpart ("fixed-partitions").
>
> Signed-off-by: Rafał Miłecki <zajec5@...il.com>
> ---
> One thing I'm not proud of in this patch is struct mtd_partition casting
> in order to be able to modify partition offset. It's marked as const so
> it was the only way I could think of. Any better ideas? Currently parser
> gets a single MTD and it doesn't have to deal with its offset, which I
> kind of like as it simplifies things.

I have to admit, I don't fully understand what you are trying to solve.
Why are you introducing a new concept of partition parsing in patch 2/2?
We have already one.

Are you unhappy with the way parsers are _requested_?
Currently MTD core tries cmdlinepart and ofpart, drivers can override that.
Do you need a way to request a parser via DT or cmdline?

-- 
Thanks,
//richard