From: Robert Jarzmik <robert.jarzmik@free.fr>
To: Brian Norris <computersforpeace@gmail.com>
Cc: Boris Brezillon <boris.brezillon@free-electrons.com>,
Marek Vasut <marex@denx.de>,
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>,
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 21:55:24 +0100 [thread overview]
Message-ID: <87eggek91f.fsf@belgarion.home> (raw)
In-Reply-To: <20151028171430.GC13239@google.com> (Brian Norris's message of "Wed, 28 Oct 2015 10:14:30 -0700")
Brian Norris <computersforpeace@gmail.com> writes:
>> >
>> > 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.
>>
>> 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).
> Yes, I think that's some of the intention there. And so even in that
> case, a multi-die chip gets represented as a single struct nand_chip.
Isn't there the case of a single NAND controller with 2 identical chips, each a
8 bit NAND chip, and the controller aggregating them to offer the OS a single
16-bit NAND chip ?
In this case, the controller (pxa3xx is a good example) will be programmed to
handle both chips at the same time, and calculate CRC on both chips, etc ... I
hope the assertion "physical chip should have its own instance of nand_chip +
mtd_info" does take into account this example.
I don't know if there is actually any user of this for either pxa3xx or another
controller, nor if there is any value in this.
Cheers.
--
Robert
next prev parent reply other threads:[~2015-10-28 21:02 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 [this message]
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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