From: Arnout Vandecappelle <arnout@mind.be>
To: linux-media@vger.kernel.org
Subject: Support for zerocopy to DSP on OMAP3
Date: Wed, 3 Mar 2010 15:12:44 +0100 [thread overview]
Message-ID: <201003031512.45428.arnout@mind.be> (raw)
Hoi,
[Please CC me, I'm not subscribed.]
I'm implementing zerocopy transfer from a v4l2 camera to the DSP on an
OMAP3 (based on earlier work by Stefan Kost [1][2]). Therefore I'm using
V4L2_MEMORY_USERPTR to pass in the memory area allocated by TI's DMAI
driver. However, this has flags VM_IO | VM_PFNMAP. This means that it is
not possible to do get_user_pages() on it - it's an area that is not
pageable and possibly even doesn't pass the MMU.
In order to support this kind of zerocopy construct, I propose to add
checks for VM_IO | VM_PFNMAP and only get pages from areas that don't have
these flags set.
If I get positive feedback on this, I'll supply a patch.
[1] https://bugzilla.gnome.org/show_bug.cgi?id=583890
[2] http://thread.gmane.org/gmane.linux.drivers.video-input-
infrastructure/6209
--
Arnout Vandecappelle arnout at mind be
Senior Embedded Software Architect +32-16-286540
Essensium/Mind http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint: 31BB CF53 8660 6F88 345D 54CC A836 5879 20D7 CF43
next reply other threads:[~2010-03-03 14:13 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-03 14:12 Arnout Vandecappelle [this message]
2010-03-03 19:11 ` [PATCH RFCv1] Support for zerocopy to DSP on OMAP3 Arnout Vandecappelle
2010-03-04 9:52 ` Laurent Pinchart
2010-03-04 16:00 ` [PATCHv2] " Arnout Vandecappelle
2010-03-04 16:00 ` [PATCH 1/2] V4L/DVB: buf-dma-sg.c: don't assume nr_pages == sglen Arnout Vandecappelle
2010-03-17 20:57 ` Sakari Ailus
2010-03-17 22:50 ` Arnout Vandecappelle
2010-03-04 16:00 ` [PATCH 2/2] V4L/DVB: buf-dma-sg.c: support non-pageable user-allocated memory Arnout Vandecappelle
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=201003031512.45428.arnout@mind.be \
--to=arnout@mind.be \
--cc=linux-media@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox