On 06/16/2009 05:45 PM, Jonathan Cameron wrote:
Guennadi Liakhovetski wrote:
On Mon, 15 Jun 2009, Jonathan Cameron wrote:
From: Jonathan Cameron <jic23@xxxxxxxxx>
OV7670 soc-camera driver. Merge of drivers from Jonathan Corbet,
Darius Augulis and Jonathan Cameron
Could you please, describe in more detail how you merged them?
Mostly by combining the various register sets and then adding pretty much
all the functionality in each of them, testing pretty much everything.
Note that a lot of what was in those drivers (usually labeled as untested)
simply doesn't work and is based on 'magic' register sets provided by
omnivision.
However, I am not sure this is the best way to go. I think, a better
approach would be to take a driver currently in the mainline, perhaps,
the most feature-complete one if there are several of them there,
That is more or less what I've done (it's based on Jonathan Corbet's
driver).
Darius' driver and mine have never been in mainline. Darius' was a
complete
rewrite based on doc's he has under NDA. Mine was based on Jonathan
Corbet's one with a few bits leveraged from a working tinyos driver
for the
platform I'm using (principally because Omnivision are ignoring both
myself
and the board supplier).
It's very difficult to write 'normal' driver for it.
Omnivision does not provide useful documentation,
only long constant arrays with few strange comments.
Beside documentation is poor, there are lot of errors in register
description.
Many things are mistery, not documented and seems Omnivision does not
have such documentation.
I thing this sensor isn't perfect for embedded projects. It's 'designed'
for webcams, where reliability and quality are not needed.
With ov7720 similar situation...
convert
it and its user(s) to v4l2-subdev, extend it with any features
missing in
it and present in other drivers, then switch users of all other ov7670
drivers over to this one,
That's the problem. The only mainlined driver is specifically for an OLPC
machine. The driver is tied to specific i2c device and doesn't use
anything
anywhere near soc-camera or v4l2-subdev.
While it would be nice to get a single driver working
for this hardware as well as more conventional soc-camera devices, it
isn't
going to happen without a lot of input from someone with an olpc. The chip
is interfaced through a Marvell 88alp101 'cafe' chip which does a
whole host
of random things alongside being video processor and taking a quick
look at
that would be written in a completely different fashion if it were
done now
(mfd with subdevices etc, v4l2-sudev)
So basically in the ideal world it would happen exactly as you've
suggested,
but I doubt it'll happen any time soon and in the meantime there is no in
kernel support for those of us using the chip on other platforms.
*looks hopefully in the direction of Jonathan Corbet and other olpc
owners*
and finally make it work with soc-camera. This
way you get a series of smaller and reviewable patches, instead of a
completely new driver, that reproduces a lot of existing code but has to
be reviewed anew. How does this sound?
Would be fine if the original driver (or anything terribly close to it)
were useable on a platform I actually have without more or less being
rewritten.
I can back track the driver to be as close to that as possible and still
functional, but I'm not entirely sure it will make the code any easier to
review and you'll loose a lot the functionality lifted from Darius' as
my original drivers.
The original posting I made was as close as you can reasonably get to
Jonathan's original driver.
http://patchwork.kernel.org/patch/12192/
At the time it wasn't really reviewed (beyond a few comments)
as you were just commencing the soc-camera conversion and it made
sense to wait for after that.
I'm not really sure how we should proceed with this. I'm particularly
loath to touch the olpc driver unless we have a reasonable number of
people willing to test.
Jonathan
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