| From: |
| Jonathan Corbet <corbet@lwn.net> |
| To: |
| linux-media@vger.kernel.org |
| Subject: |
| [RFC] Second marvell-cam patch series |
| Date: |
| Mon, 20 Jun 2011 13:14:35 -0600 |
| Message-ID: |
| <1308597280-138673-1-git-send-email-corbet@lwn.net> |
| Cc: |
| g.liakhovetski@gmx.de, Kassey Lee <ygli@marvell.com> |
| Archive-link: |
| Article, Thread
|
OK, here's my second series of marvell-cam patches for comment; the main
thing here is (finally) the addition of videobuf2 vmalloc and dma-contig
support. Anybody who would just rather look at the final product can grab:
git://git.lwn.net/linux-2.6.git mmp-linuxtv
There is one real mystery here; ideas would be welcome. When I switch to
contiguous DMA mode, mplayer gets faster as one might expect - copying all
those frames in the kernel hurts. But a basic gstreamer pipeline:
gst-launch v4l2src ! ffmpegcolorspace ! videoscale ! ximagesink
slows down by a factor of two. Somehow the gst-launch binary finds a way
to use twice as much time processing frames. Given that the difference
should not really even be visible to user space, I'm at a total loss here.
In this series:
Jonathan Corbet (5):
marvell-cam: convert to videobuf2
marvell-cam: include file cleanup
marvell-cam: no need to initialize the DMA buffers
marvell-cam: Don't spam the logs on frame loss
marvell-cam: implement contiguous DMA operation
Kconfig | 4
cafe-driver.c | 6
mcam-core.c | 785 +++++++++++++++++++++++++---------------------------------
mcam-core.h | 47 ++-
mmp-driver.c | 1
5 files changed, 387 insertions(+), 456 deletions(-)
Todo items at this point:
- Scatter/gather DMA support (probably)
- Eliminate ov7670 assumptions
- Userptr support (should Just Work in DMA-contiguous mode)
Comments?
Thanks,
jon