From: Sascha Hauer <s.hauer@pengutronix.de>
To: Dave Kitchen <dave.kitchen@insync.tv>
Cc: barebox@lists.infradead.org
Subject: Re: MTD with non-power-of-2 page size
Date: Wed, 19 Aug 2015 16:20:20 +0200 [thread overview]
Message-ID: <20150819142020.GF18700@pengutronix.de> (raw)
In-Reply-To: <55CB2C1C.4000002@insync.tv>
Hi Dave,
On Wed, Aug 12, 2015 at 12:21:00PM +0100, Dave Kitchen wrote:
>
> I have just started to work with barebox on an Atmel at91sam9g45 processor.
> The board has an Atmel AT45DB161 dataflash configured as 528-byte page size.
> I find that eg saveenv command does not run as the page erase fails
> with EINVAL. On tracing this is fired from the page size and offset
> correction code [mtd/core,c mtd_erase_align()] which uses bit
> masking to align the size and offset. Unfortunately bit-masking does
> not work with non-power-of-2 pages. Has anyone else addressed this
> problem?
>
> The 'trivial' exercise of replacing the bit masks by modulo [%]
> operator does not succeed as the compiler I am using (gcc!) does not
> support long-long divmod.
You could use do_div here which returns the remainder. Also see the
mtd_div_by_eb() and mtd_mod_by_eb() functions which may be what you are
looking for.
Sascha
--
Pengutronix e.K. | |
Industrial Linux Solutions | http://www.pengutronix.de/ |
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next prev parent reply other threads:[~2015-08-19 14:20 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-12 11:21 Dave Kitchen
2015-08-12 12:13 ` Simon Aittamaa
2015-08-19 14:20 ` Sascha Hauer [this message]
2015-08-19 14:29 ` Dave Kitchen
2015-08-19 14:45 ` Sascha Hauer
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