From: Brian Norris <computersforpeace@gmail.com>
To: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org,
Ezequiel Garcia <ezequiel.garcia@free-electrons.com>,
Marek Vasut <marex@denx.de>, 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: Tue, 27 Oct 2015 10:54:46 -0700 [thread overview]
Message-ID: <20151027175446.GT13239@google.com> (raw)
In-Reply-To: <20151027084200.2434180f@bbrezillon>
Hi Boris,
On Tue, Oct 27, 2015 at 08:42:00AM +0100, Boris Brezillon wrote:
> On Mon, 26 Oct 2015 19:31:06 -0700
> Brian Norris <computersforpeace@gmail.com> wrote:
>
> > It seems more logical to use a device node directly associated with the
> > MTD master device (i.e., mtd->dev.of_node field) rather than requiring
> > auxiliary partition parser information to be passed in by the driver in
> > a separate struct.
> >
> > This patch supports the mtd->dev.of_node field, deprecates the parser
> > data 'of_node' field, and begins using the new convention for nand_base.
> > Other NAND driver conversions may now follow.
> >
> > Additional side benefit to assigning mtd->dev.of_node rather than using
> > parser data: the driver core will automatically create a device -> node
> > symlink for us.
>
> I like the idea, but how about pushing the solution even further and
> killing the ->flash_node field which AFAICT is rendered useless by
> your patch?
I suppose we could do that. I do think there's something to be said for
layering, though. Historically, we haven't done a very good job of
layering in MTD, so low-level drivers often have to poke around in the
MTD structures, even if they really should only have to know a few
things about their helper subsystem/library, like NAND or SPI NOR. So
with that in mind, I think the ->flash_node serves some purpose --
drivers can just initialize struct nand_chip/spi_nor and be assured that
the NAND/SPI-NOR subsystems will take care of things.
Now, I don't think there's much reason to suspect that we'd have a more
complex mapping than 1:1 between struct mtd_info and struct nand_chip or
struct spi_nor, so maybe we don't actually need duplicate storage
(mtd.dev.of_node and {spi_nor,nand_chip}.flash_node), and the layering
is just have these APIs:
nand_set_flash_node()
spi_nor_set_flash_node()
which just call mtd_set_of_node()?
Speaking of layering: why do we have NAND drivers initializing mtd->priv
for us, yet nand_base just assumes that it points to a struct nand_chip?
And why isn't struct mtd_info just embedded in struct nand_chip? Are
there ever cases we want more than one (master) MTD per nand_chip? Or
vice versa?
Thanks for the review,
Brian
next prev parent reply other threads:[~2015-10-27 17:54 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 [this message]
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
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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