From: Bernhard Frauendienst <kernel@nospam.obeliks.de>
To: Rob Herring <robh+dt@kernel.org>
Cc: "David Woodhouse" <dwmw2@infradead.org>,
"Brian Norris" <computersforpeace@gmail.com>,
"Boris Brezillon" <boris.brezillon@bootlin.com>,
"Marek Vašut" <marek.vasut@gmail.com>,
"Richard Weinberger" <richard@nod.at>,
"Mark Rutland" <mark.rutland@arm.com>,
"Miquèl Raynal" <miquel.raynal@bootlin.com>,
"MTD Maling List" <linux-mtd@lists.infradead.org>,
devicetree@vger.kernel.org,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 3/3] mtd: mtdconcat: add dt driver for concat devices
Date: Fri, 14 Sep 2018 15:42:46 +0200 [thread overview]
Message-ID: <20180914134246.GB5913@dellux> (raw)
In-Reply-To: <CAL_JsqL+CMzkyeHLxa+6xf0FkM3mSPiGvoMrRoVV-FS1Q7SQsA@mail.gmail.com>
Hi Rob,
sorry it took me so long to reply, I had to set up mutt first ;)
On Mon, Sep 10, 2018 at 04:47:22PM -0500, Rob Herring wrote:
> On Sat, Sep 8, 2018 at 8:20 AM Bernhard Frauendienst
> <kernel@nospam.obeliks.de> wrote:
> >
> > Some mtd drivers like physmap variants have support for concatenating
> > multiple mtd devices, but there is no generic way to define such a
> > concat device from within the device tree.
>
> That is the generic way, but I suppose that only works for parallel
> memory mapped devices. So is it just spi-nor that you need to support?
I'm no expert in this domain, or regarding OpenWRT, but as far as I can
tell this only concerns spi-nor devices. It definitely does in my
specific use-case.
> Can we just make reg take multiple chip selects just like the existing
> support takes multiple reg entries?
That sounds like an interesting idea, but I'm afraid it's not a trivial
change, as far as I can tell from looking at spi.c.
The 'reg' property is currently read in of_spi_parse_dt which gets
passed the spi device created in of_register_spi_device. The latter
would have to create multiple devices from a single OF node, and pass
the chipselect value to of_spi_parse_dt, which would have to parse the
same node multiple times, which feels a bit strange. To make things
worse, of_register_spi_device returns the created device, although that
value seems unused in the current tree (except for error checks).
Am I correct to assume that this change in method signature could be
accteptable since both functions are not exported?
Regards,
Bernhard
prev parent reply other threads:[~2018-09-14 13:42 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-08 13:13 [PATCH v3 0/3] mtd concat device driver Bernhard Frauendienst
2018-09-08 13:13 ` [PATCH v3 1/3] mtd: core: add get_mtd_device_by_node Bernhard Frauendienst
2018-09-08 13:13 ` [PATCH v3 2/3] dt-bindings: add bindings for mtd-concat devices Bernhard Frauendienst
2018-09-10 10:51 ` Rafał Miłecki
2018-09-10 12:13 ` Bernhard Frauendienst
2018-09-10 12:17 ` Bernhard Frauendienst
2018-09-08 13:13 ` [PATCH v3 3/3] mtd: mtdconcat: add dt driver for concat devices Bernhard Frauendienst
2018-09-10 21:47 ` Rob Herring
2018-09-14 13:42 ` Bernhard Frauendienst [this message]
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