Re: [RFC PATCH] [media] mt9v032: Add support for mt9v022 and mt9v024

Philipp Zabel
2014-05-28T14:36:58Z

Hi Guennadi, Laurent,

Am Mittwoch, den 28.05.2014, 13:04 +0200 schrieb Laurent Pinchart:
> Hello,
>
> On Wednesday 28 May 2014 12:07:57 Guennadi Liakhovetski wrote:
> > On Wed, 28 May 2014, Philipp Zabel wrote:
> > > Am Dienstag, den 27.05.2014, 21:48 +0200 schrieb Guennadi Liakhovetski:
> > > > On Mon, 26 May 2014, Philipp Zabel wrote:
> > > > > From the looks of it, mt9v022 and mt9v032 are very similar,
> > > > > as are mt9v024 and mt9v034. With minimal changes it is possible
> > > > > to support mt9v02[24] with the same driver.
> > > >
> > > > Are you aware of drivers/media/i2c/soc_camera/mt9v022.c?
> > >
> > > Yes. Unfortunately this driver can't be used in a system without
> > > soc_camera. It uses soc_camera helpers and doesn't implement pad ops
> > > among others.
> >
> > As I mentioned many times, this compatibility is a matter of someone just
> > needing and finally doing this. If you need this, please, extend the
> > mt9v022 driver to also work with non soc-camera hosts, if you need any
> > help - please feel free to ask, I can send you my conversion code, that
> > I've done for ov772x, but never managed to finalise testing,
> > unfortunately.
> >
> > > > With this patch you'd duplicate support for both mt9v022 and mt9v024,
> > > > which doesn't look like a good idea to me.
> > >
> > > While this is true, given that the mt9v02x/3x sensors are so similar,
> > > the support is already duplicated in all but name.
> > > Would you suggest we should try to merge the mt9v032 and mt9v022
> > > drivers?
> >
> > Out of 3 options:
> >
> > 1. extend mt9v022 to work with non soc-camera hosts
> > 2. extend mt9v032 to also support mt9v022 and mt9v024
> > 3. merge both mt9v022 and mt9v032 drivers
> >
> > option 2 seems the worst to me.

It also is the easiest to achieve and the mt9v032 driver is prettier (as
in doesn't have support for the external gpio bus shifter, which I don't
think belongs in the sensor driver).

> > I'm ok with either 1 or 3, whereas 3 is
> > more difficult than 1.
>
> This topic has been discussed over and over. It indeed "just" requires someone
> to do it, although it might be more complex than that sounds.
>
> We need to fix the infrastructure to make sensor drivers completely unaware of
> soc-camera. This isn't about extending the mt9v022 driver to work with non
> soc-camera hosts, it's about fixing soc-camera not to require any change to
> sensor drivers. Philipp, if you have time to work on that, we can discuss what
> needs to be done.

I don't have a use case for soc_camera. Instead of trying to fix it to
use generic sensor drivers, I'd rather use that time to prepare
non-soc_camera capture host support.

> On the sensor side, we should have a single driver for the mt9v022, 024 and
> 032 sensors. I would vote for merging the two drivers into
> drivers/media/i2c/mt9v032.c, as that one is closer to the goal of not being
> soc-camera specific.

regards
Philipp