linux-kernel - RE: [PATCH 1/2] mtdpart: memory accessor interface for MTD layer

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Message-ID: <1280920127.19499.20.camel@localhost>
Date:	Wed, 04 Aug 2010 12:08:47 +0100
From:	David Woodhouse <dwmw2@...radead.org>
To:	David Brownell <david-b@...bell.net>
Cc:	'Kevin Hilman' <khilman@...prootsystems.com>,
	Sudhakar Rajashekhara <sudhakar.raj@...com>,
	'Bernd Schmidt' <bernd.schmidt@...log.com>,
	'Nicolas Pitre' <nico@...xnic.net>,
	linux-kernel@...r.kernel.org,
	'David Howells' <dhowells@...hat.com>,
	'David Brownell' <dbrownell@...rs.sourceforge.net>,
	linux-mtd@...ts.infradead.org,
	'Andrew Morton' <akpm@...ux-foundation.org>
Subject: RE: [PATCH 1/2] mtdpart: memory accessor interface for MTD layer

On Wed, 2010-08-04 at 03:31 -0700, David Brownell wrote:
> Point is to ensure that enough of the right context
> information is available to initialize correctly.
> So the right data is extracted and passed on.

Forgive me if I'm being dim (and in particular, please forgive me if I'm
going over something that was already discussed; I know it's been a
while). But I don't see why it needs to be passed through the core MTD
code.

To take the simple case of an unpartitioned MTD device -- why can't the
map driver (or whatever) just call the maccessor setup function for
itself, directly, right after calling add_mtd_device() with its
newly-probed MTD device?

And for partitions, why can't it do the same, on the appropriate
partition.

OK, the answer to the latter question is that you don't actually *have*
the pointers to each partition you register. But that's easily fixed.

If we make add_mtd_partitions() take an extra 'struct mtd_info **'
argument and put pointers to the slave mtd 'devices' into that, it means
that your board driver *can* reliably get the mtd pointer for the fourth
partition, or whatever it needs. And can then just do the memory
accessor setup for itself.

Isn't that enough?

-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse@...el.com                              Intel Corporation

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