From: Marek Vasut <marex@denx.de>
To: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Brian Norris <computersforpeace@gmail.com>,
linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org,
Ezequiel Garcia <ezequiel.garcia@free-electrons.com>,
Scott Wood <scottwood@freescale.com>, Josh Wu <josh.wu@atmel.com>,
Robert Jarzmik <robert.jarzmik@free.fr>,
Kyungmin Park <kyungmin.park@samsung.com>,
Han Xu <han.xu@freescale.com>,
Huang Shijie <shijie.huang@arm.com>
Subject: Re: [PATCH 1/5] mtd: ofpart: grab device tree node directly from master device node
Date: Wed, 28 Oct 2015 21:38:20 +0100 [thread overview]
Message-ID: <201510282138.20754.marex@denx.de> (raw)
In-Reply-To: <20151028173215.0c1c4e30@bbrezillon>
On Wednesday, October 28, 2015 at 05:32:15 PM, Boris Brezillon wrote:
> Hi Marek,
Hi Boris,
> On Wed, 28 Oct 2015 17:11:14 +0100
>
> Marek Vasut <marex@denx.de> wrote:
> > On Wednesday, October 28, 2015 at 08:58:13 AM, Boris Brezillon wrote:
> > > Hi Brian,
> >
> > Hi,
> >
> > [...]
> >
> > > > Are
> > > > there ever cases we want more than one (master) MTD per nand_chip? Or
> > > > vice versa?
> > >
> > > Nope, I'd say that you always have a 1:1 relationship between a master
> > > MTD device and a NAND device.
> >
> > Do some sorts of chipselects come into play here ? Ie. you can have one
> > master with multiple NAND chips connected to it.
>
> Most NAND controllers support interacting with several chips (or
> dies in case your chip embeds several NAND dies), but I keep thinking
> each physical chip should have its own instance of nand_chip + mtd_info.
> If you want to have a single mtd device aggregating several chips you
> can use mtdconcat.
I agree.
> This leaves the multi-dies chip case, and IHMO we should represent those
> chips as a single entity, and I guess that's the purpose of the
> ->numchips field in nand_chip (if your chip embeds 2 dies with 2 CS
> lines, then ->numchips should be 2).
I'd expect this to be represented as two physical chips, no ?
> Anyway, I think the whole problem here is that most NAND drivers are
> mixing the concepts of NAND controller (the controller driving one or
> several NAND chips) and NAND chip (a chip connected to a NAND
> controller).
> The NAND controller should not be represented with a nand_chip
> instance, but with a nand_hw_control instance, which is rarely done
> except in a few drivers.
OK, understood.
> I sent an RFC a while ago [1] to clarify that, but didn't have time to
> post a new version.
>
> Best Regards,
>
> Boris
>
> [1]http://thread.gmane.org/gmane.linux.drivers.mtd/57614/focus=58552
Best regards,
Marek Vasut
next prev parent reply other threads:[~2015-10-28 20:38 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-27 2:31 [PATCH 0/5] mtd: migrate 'of_node' handling to core, not in mtd_part_parser_data Brian Norris
2015-10-27 2:31 ` [PATCH 1/5] mtd: ofpart: grab device tree node directly from master device node Brian Norris
2015-10-27 7:42 ` Boris Brezillon
2015-10-27 17:54 ` Brian Norris
2015-10-28 1:01 ` Brian Norris
2015-10-28 8:02 ` Boris Brezillon
2015-10-28 7:58 ` Boris Brezillon
2015-10-28 16:11 ` Marek Vasut
2015-10-28 16:32 ` Boris Brezillon
2015-10-28 17:14 ` Brian Norris
2015-10-28 20:55 ` Robert Jarzmik
2015-10-28 22:47 ` Marek Vasut
2015-10-29 6:32 ` Robert Jarzmik
2015-10-29 7:24 ` Boris Brezillon
2015-10-29 17:23 ` Marek Vasut
2015-10-29 17:34 ` Boris Brezillon
2015-10-29 20:28 ` Robert Jarzmik
2015-10-28 20:38 ` Marek Vasut [this message]
2015-10-27 2:31 ` [PATCH 2/5] mtd: nand: drop unnecessary partition parser data Brian Norris
2015-10-27 7:52 ` Boris Brezillon
2015-10-28 0:45 ` Brian Norris
2015-10-27 2:31 ` [PATCH 3/5] mtd: spi-nor: " Brian Norris
2015-10-27 2:31 ` [PATCH 4/5] mtd: " Brian Norris
2015-10-27 2:31 ` [PATCH 5/5] mtd: drop 'of_node' " Brian Norris
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