From: Dan Malek <dan@embeddededge.com>
To: Sergio Ruiz <quekio@gmail.com>
Cc: linux-mips@linux-mips.org
Subject: Re: How to the the physical addresses under linux (au1500)
Date: Tue, 3 May 2005 16:09:58 -0400 [thread overview]
Message-ID: <f2bcc2c8588140446359a0f5f5cf78ca@embeddededge.com> (raw)
In-Reply-To: <e02bc66105050312564d0dacdb@mail.gmail.com>
On May 3, 2005, at 3:56 PM, Sergio Ruiz wrote:
> I am trying to program the DMA (with the ac97) in assembler using a
> linux kernel module for mips teaching purposes.
I think you want to choose a more simple teaching example :-)
> Looking at the kernel source code, I found that I can get the physical
> address subtracting 0x8000000, but It doesnt seem to work.
Not always. On systems like this one that are not cache coherent,
we play games with mapped addresses to get uncached spaces
or you need to apply various macros/functions to keep the space
coherent.
> Any idea?
Use a more simple example. Maybe just update one of the
LED displays on the board.
-- Dan
next prev parent reply other threads:[~2005-05-03 20:10 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-05-03 19:56 How to the the physical addresses under linux (au1500) Sergio Ruiz
2005-05-03 20:09 ` Dan Malek [this message]
-- strict thread matches above, loose matches on Subject: below --
2005-05-03 21:04 Sergio Ruiz
2005-05-03 21:49 ` Wolfgang Denk
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