On Monday 30 November 2009 15:48:24 Guennadi Liakhovetski wrote:
> On Mon, 30 Nov 2009, Hans Verkuil wrote:
> > On Fri, 27 Nov 2009, Guennadi Liakhovetski wrote:
> > > On Fri, 27 Nov 2009, Hans Verkuil wrote:
> > > > Hi Guennadi,
> > > >
> > > > > Convert soc-camera core and all soc-camera drivers to the new
> > > > > mediabus API. This also takes soc-camera client drivers one step
> > > > > closer to also be
> > > > > usable with generic v4l2-subdev host drivers.
> > > >
> > > > Just a quick question:
> > > > > @@ -323,28 +309,39 @@ static int mt9m001_s_fmt(struct v4l2_subdev
> > > > > *sd, struct v4l2_format *f)
> > > > > /* No support for scaling so far, just crop. TODO: use skipping
> > > > > */ ret = mt9m001_s_crop(sd, &a);
> > > > > if (!ret) {
> > > > > - pix->width = mt9m001->rect.width;
> > > > > - pix->height = mt9m001->rect.height;
> > > > > - mt9m001->fourcc = pix->pixelformat;
> > > > > + mf->width = mt9m001->rect.width;
> > > > > + mf->height = mt9m001->rect.height;
> > > > > + mt9m001->fmt = soc_mbus_find_datafmt(mf->code,
> > > > > + mt9m001->fmts,
> > > > > mt9m001->num_fmts);
> > > > > + mf->colorspace = mt9m001->fmt->colorspace;
> > > > > }
> > > > >
> > > > > return ret;
> > > > > }
> > > > >
> > > > > -static int mt9m001_try_fmt(struct v4l2_subdev *sd, struct
> > > > > v4l2_format *f)
> > > > > +static int mt9m001_try_fmt(struct v4l2_subdev *sd,
> > > > > + struct v4l2_mbus_framefmt *mf)
> > > > > {
> > > > > struct i2c_client *client = sd->priv;
> > > > > struct mt9m001 *mt9m001 = to_mt9m001(client);
> > > > > - struct v4l2_pix_format *pix = &f->fmt.pix;
> > > > > + const struct soc_mbus_datafmt *fmt;
> > > > >
> > > > > - v4l_bound_align_image(&pix->width, MT9M001_MIN_WIDTH,
> > > > > + v4l_bound_align_image(&mf->width, MT9M001_MIN_WIDTH,
> > > > > MT9M001_MAX_WIDTH, 1,
> > > > > - &pix->height, MT9M001_MIN_HEIGHT + mt9m001->y_skip_top,
> > > > > + &mf->height, MT9M001_MIN_HEIGHT + mt9m001->y_skip_top,
> > > > > MT9M001_MAX_HEIGHT + mt9m001->y_skip_top, 0, 0);
> > > > >
> > > > > - if (pix->pixelformat == V4L2_PIX_FMT_SBGGR8 ||
> > > > > - pix->pixelformat == V4L2_PIX_FMT_SBGGR16)
> > > > > - pix->height = ALIGN(pix->height - 1, 2);
> > > > > + if (mt9m001->fmts == mt9m001_colour_fmts)
> > > > > + mf->height = ALIGN(mf->height - 1, 2);
> > > > > +
> > > > > + fmt = soc_mbus_find_datafmt(mf->code, mt9m001->fmts,
> > > > > + mt9m001->num_fmts);
> > > > > + if (!fmt) {
> > > > > + fmt = mt9m001->fmt;
> > > > > + mf->code = fmt->code;
> > > > > + }
> > > > > +
> > > > > + mf->colorspace = fmt->colorspace;
> > > > >
> > > > > return 0;
> > > > > }
> > > >
> > > > Why do the sensor drivers use soc_mbus_find_datafmt? They only seem
> > > > to be interested in the colorspace field, but I don't see the reason
> > > > for that. Most if not all sensors have a fixed colorspace depending
> > > > on the pixelcode, so they can just ignore the colorspace that the
> > > > caller requested and replace it with their own.
> > >
> > > Right, that's exactly what's done here. mt9m001 and mt9v022 drivers
> > > support different formats, depending on the exact detected or specified
> > > by the user model. That's why they have to search for the requested
> > > format in supported list. and then - yes, they just put the found
> > > format into user
> > >
> > > request:
> > > > > + mf->colorspace = fmt->colorspace;
> > > >
> > > > I didn't have time for a full review, so I might have missed
> > > > something.
> >
> > I looked at this more closely and I realized that I did indeed miss that
> > soc_mbus_find_datafmt just searched in the pixelcode -> colorspace
> > mapping array.
> >
> > I also realized that there is no need for that data structure and
> > function to be soc-camera specific. I believe I said otherwise in an
> > earlier review. My apologies for that, all I can say is that I had very
> > little time to do the reviews...
>
> No, you did not say otherwise about _these_ struct and function - they
> only appeared in v2 of the mediabus API, after you'd suggested to move
> colorspace into struct v4l2_mbus_framefmt.
>
> > That said, there is no need for both the soc_mbus_datafmt struct and the
> > soc_mbus_find_datafmt function. These can easily be replaced by something
> > like this as a local function in each subdev:
> >
> > static enum v4l2_colorspace mt9m111_g_colorspace(enum v4l2_mbus_pixelcode
> > code)
> > {
> > switch (code) {
> > case V4L2_MBUS_FMT_YUYV:
> > case V4L2_MBUS_FMT_YVYU:
> > case V4L2_MBUS_FMT_UYVY:
> > case V4L2_MBUS_FMT_VYUY:
> > return V4L2_COLORSPACE_JPEG;
> >
> > case V4L2_MBUS_FMT_RGB555:
> > case V4L2_MBUS_FMT_RGB565:
> > case V4L2_MBUS_FMT_SBGGR8:
> > case V4L2_MBUS_FMT_SBGGR10_2X8_PADHI_LE:
> > return V4L2_COLORSPACE_SRGB;
> >
> > default:
> > return 0;
> > }
> > }
> >
> > So if mt9m111_g_colorspace() returns 0, then the format wasn't found.
> > (Note that the compiler might give a warning for the return 0, so that
> > might need some editing)
> >
> > Much simpler and much easier to understand.
>
> Drivers are not forced to use that small and trivial function - everyone
> is welcome to reinvent the wheel:-) In many cases it is indeed an
> overkill, like mt9t031, which only supports one format. However, in some
> other drivers this is not that trivial. First, as I said, mt9m001 and
> mt9v022 generate that array dynamically, depending on the chip version and
> platform configuration. So, you anyway would have to iterate over the
> array. In other drivers, like ov772x and the recently submitted mt9t112
> this function is also used to retrieve register configuration for a
> specific pixel code. So, I still think that function is useful, and being
> kept under soc-camera mediabus extensions, and being inline, it shouldn't
> cause too many problems.
It definitely shouldn't be in a soc-camera header. If this is going to be used
as a common utility, then it should be in v4l2-mediabus.h.
But frankly the only two places where I think it is useful are mt9m001 and
mt9v022. In all other cases is can be replaced by simpler code. For ov772x
I would just add the pixelcode and colorspace fields to the
ov772x_color_format struct instead and you iterate of the elements of the
ov772x_cfmts array to find the one that matches the desired pixelcode.
I think the usefulness of the datastructure and utility function depends very
much on the sensor driver which is why I prefer to have this being just part
of the driver source itself rather than in a generic header. That gives the
impression that driver writers *have* to do it that way, when often it can be
done much simpler.
Regards,
Hans
>
> Thanks
> Guennadi
> ---
> Guennadi Liakhovetski
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