From: Robert Jarzmik <robert.jarzmik@free.fr>
To: Mike Rapoport <mike@compulab.co.il>
Cc: video4linux-list@redhat.com
Subject: Re: pxa_camera: DMA alignment requirement
Date: Tue, 25 Nov 2008 22:18:46 +0100 [thread overview]
Message-ID: <87ljv7a4i1.fsf@free.fr> (raw)
In-Reply-To: <491FCBFF.9060208@compulab.co.il> (Mike Rapoport's message of "Sun\, 16 Nov 2008 09\:30\:07 +0200")
Mike Rapoport <mike@compulab.co.il> writes:
>>>From what I read on the PXA manual, the only constraint is 16bytes
>> alignement. Would you also remember who wrote the code, so that I can ask him
>> where he read about page alignement constraint please ?
>
> Just by coincidence it was me :)
> I used pxafb_overlay from [1], and my (mis)understanding of what it does added
> the page alignment constrain. Now looking at the overlay code once more, I'm not
> sure if it's necessary.
>
> ---
> [1] http://www.rpsys.net/openzaurus/patches/archive/pxa27x_overlay-r8.patch
Just for the record, I made a try or two, changing the alignment from page (4096
bytes) into 16 bytes (PAGE_ALIGN -> ALIGN(x,16)). And surprise, I get a lot of
DMA bus errors ...
I'm still investigating, there's something weird in there ...
Cheers.
--
Robert
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prev parent reply other threads:[~2008-11-26 0:13 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-11-09 17:01 pxa_camera: DMA alignment requirement Robert Jarzmik
2008-11-13 10:23 ` Mike Rapoport
2008-11-16 1:14 ` Robert Jarzmik
2008-11-16 7:30 ` Mike Rapoport
2008-11-25 21:18 ` Robert Jarzmik [this message]
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