From: "Albrecht Dreß" <albrecht.dress@arcor.de>
To: Wolfram Sang <w.sang@pengutronix.de>
Cc: devicetree-discuss@ozlabs.org, linuxppc-dev@ozlabs.org,
linux-mtd@lists.infradead.org, Ben Dooks <ben-linux@fluff.org>,
David Woodhouse <dwmw2@infradead.org>
Subject: Re: [PATCH V2 2/2] mtd/maps/mtd-ram: add an of-platform driver
Date: Mon, 08 Jun 2009 19:30:45 +0200 [thread overview]
Message-ID: <1244482256.3278.0@antares> (raw)
In-Reply-To: <20090608163540.GA16384@pengutronix.de> (from w.sang@pengutronix.de on Mon Jun 8 18:35:40 2009)
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Am 08.06.09 18:35 schrieb(en) Wolfram Sang:
>> Question: why is bank-width even relevant for a RAM device?
>
> The underlying map_ram-driver uses it once while erasing. The
> question remains if this is really needed?
Am 06.06.09 18:16 schrieb(en) Albrecht Dreß:
> At least if the RAM is attached to the 5200's Local Plus Bus in
> 16-bit mode, no byte write accesses are allowed (byte /reads/ work,
> though). I have a tweak (which I will post next week) to address
> this case, which depends upon this setting.
To put this clearer: on '5200 based systems, the driver (more specific:
the function inline_map_copy_to()) *must* know whether the hardware is
connected in 8-bit or 16-bit mode to the Local Plus Bus, as byte writes
(issued by memcpy_toio()) will fail for the latter setup (probably the
same applies for byte and word writes in 32-bit mode).
IMHO, this information should be passed using the device tree. The
"bank-width" seems to be an obvious choice for that.
Best, Albrecht.
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next prev parent reply other threads:[~2009-06-08 17:31 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-05 12:05 [PATCH V2 0/2] mtd/maps/mtd-ram: Make driver usable for the device tree Wolfram Sang
2009-06-05 12:05 ` [PATCH V2 1/2] mtd/maps/mtd-ram: refactor probe and remove Wolfram Sang
2009-06-05 12:05 ` [PATCH V2 2/2] mtd/maps/mtd-ram: add an of-platform driver Wolfram Sang
2009-06-05 15:53 ` Grant Likely
2009-06-05 16:22 ` Albrecht Dreß
2009-06-06 8:14 ` David Woodhouse
2009-06-06 11:19 ` Wolfram Sang
2009-06-16 9:09 ` Wolfram Sang
2009-06-06 16:05 ` Grant Likely
2009-06-06 16:16 ` Albrecht Dreß
2009-06-08 16:35 ` Wolfram Sang
2009-06-08 17:30 ` Albrecht Dreß [this message]
2009-06-15 17:43 ` Albrecht Dreß
2009-06-16 9:18 ` Wolfram Sang
2009-06-16 12:53 ` Grant Likely
2009-06-16 13:20 ` Wolfram Sang
[not found] ` <fa686aa40906160833g1d77466ekf8b8d4350ab32a24@mail.gmail.com>
2009-06-16 15:34 ` Grant Likely
2009-06-16 17:19 ` Albrecht Dreß
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