linux-kernel - Re: [PATCH 3/4] mtd: mchp23k256: add partitioning support

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Message-ID: <20170608232110.GG102137@google.com>
Date:   Thu, 8 Jun 2017 16:21:10 -0700
From:   Brian Norris <computersforpeace@...il.com>
To:     Boris Brezillon <boris.brezillon@...e-electrons.com>
Cc:     Chris Packham <chris.packham@...iedtelesis.co.nz>,
        dwmw2@...radead.org, andrew@...n.ch, linux-mtd@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Marek Vasut <marek.vasut@...il.com>,
        Richard Weinberger <richard@....at>,
        Cyrille Pitchen <cyrille.pitchen@...ev4u.fr>
Subject: Re: [PATCH 3/4] mtd: mchp23k256: add partitioning support

On Fri, Jun 02, 2017 at 11:04:06AM +0200, Boris Brezillon wrote:
> BTW, MTD_NO_ERASE is not the only problem we have with UBI or JFFS2.
> Are we guaranteed that an erase operation fills an eraseblock with
> ones? Don't we have mem technologies that are filling them with zeros?
> Note that mtdram is artificially setting the mem-region to 0xff in its
> dummy erase operation, so maybe it's a implicit rule that ->_erase() is
> supposed to fill eraseblocks with 0xff.

I've wondered about the general assumption. But mtdram isn't really a
good example, because it clearly calls itself a "test mtd device". So it
makes sense it would emulate common MTDs (i.e., flash memory).

Brian