On Fri, 28 Sep 2012, Anatolij Gustschin wrote:
> Hi Guennadi,
>
> On Fri, 28 Sep 2012 14:33:34 +0200 (CEST)
> Guennadi Liakhovetski <g.liakhovetski@xxxxxx> wrote:
> ...
> > > @@ -235,12 +238,32 @@ static int mt9v022_s_stream(struct v4l2_subdev *sd, int enable)
> > > struct i2c_client *client = v4l2_get_subdevdata(sd);
> > > struct mt9v022 *mt9v022 = to_mt9v022(client);
> > >
> > > - if (enable)
> > > + if (enable) {
> > > /* Switch to master "normal" mode */
> > > mt9v022->chip_control &= ~0x10;
> > > - else
> > > + if (is_mt9v022_rev3(mt9v022->chip_version) ||
> > > + is_mt9v024(mt9v022->chip_version)) {
> > > + /*
> > > + * Unset snapshot mode specific settings: clear bit 9
> > > + * and bit 2 in reg. 0x20 when in normal mode.
> > > + */
> > > + if (reg_clear(client, MT9V022_REG32, 0x204))
> > > + return -EIO;
> > > + }
> > > + } else {
> > > /* Switch to snapshot mode */
> > > mt9v022->chip_control |= 0x10;
> > > + if (is_mt9v022_rev3(mt9v022->chip_version) ||
> > > + is_mt9v024(mt9v022->chip_version)) {
> > > + /*
> > > + * Required settings for snapshot mode: set bit 9
> > > + * (RST enable) and bit 2 (CR enable) in reg. 0x20
> > > + * See TechNote TN0960 or TN-09-225.
> > > + */
> > > + if (reg_set(client, MT9V022_REG32, 0x204))
> > > + return -EIO;
> > > + }
> > > + }
> >
> > Do I understand it right, that now on mt9v022 rev.3 and mt9v024 you
> > unconditionally added using REG32 for leaving the snapshot mode on
> > streamon and entering it on streamoff. This should be ok in principle,
> > since that's also what we're trying to do, using the CHIP_CONTROL
> > register. But in your comment you say, that on some _systems_ you can only
> > _operate_ in snapshot mode. I.e. the snapshot mode enabled during running
> > streaming, right? Then how does this patch help you with that?
>
> Yes. But i.e. the driver calling the sub-device stream control function
> on streamon knows that the normal mode is not supported and therefore it
> calls this function with argument enable == 0, effectively setting the
> snapshot mode.
Right, I thought you could be doing that... Well, on the one hand I should
be happy, that the problem is solved without driver modifications, OTOH
this isn't pretty... In fact this shouldn't work at all. After a
stream-off the buffer queue should be stopped too. However, to properly
implement this you'd have to add a new V4L2 control to switch into
snapshot mode.
Thanks
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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