From: linux@arm.linux.org.uk (Russell King - ARM Linux)
To: linux-arm-kernel@lists.infradead.org
Subject: [i2c-mxs] Broken DMA operations from within a module
Date: Wed, 13 Feb 2013 12:14:50 +0000 [thread overview]
Message-ID: <20130213121450.GA17833@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <lyehgkift9.fsf@ensc-virt.intern.sigma-chemnitz.de>
On Wed, Feb 13, 2013 at 01:00:50PM +0100, Enrico Scholz wrote:
> E.g. when doing something like
>
> struct i2c_msg xfer = {
> .buf = "something",
> ...
> };
>
> ret = i2c_transfer(client->adapter, &xfer, 1);
>
> random data will be sent because buf is not DMA mapable ("something" is
> located in the .strtab section within module memory). MXS has a memory
> layout like
DMA buffers must be located in lowmem *always*. This means placing them
in the .data segment does not work. USB has been through this already
and it's well known there...
next prev parent reply other threads:[~2013-02-13 12:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-13 12:00 [i2c-mxs] Broken DMA operations from within a module Enrico Scholz
2013-02-13 12:14 ` Russell King - ARM Linux [this message]
2013-02-13 12:28 ` Enrico Scholz
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