Re: [PATCH v3 1/4] [media] exynos-gsc: Use 576p instead 720p as a threshold for colorspaces

[Thibault Saunier]

On 02/10/2017 12:07 PM, Hans Verkuil wrote:
> On 02/10/2017 03:10 PM, Thibault Saunier wrote:
> > From: Javier Martinez Canillas <javier@xxxxxxxxxxxxxxx>
> >
> > The media documentation says that the V4L2_COLORSPACE_SMPTE170M colorspace
> > should be used for SDTV and V4L2_COLORSPACE_REC709 for HDTV. But drivers
> > don't agree on the display resolution that should be used as a threshold.
> >
> > Some drivers set V4L2_COLORSPACE_REC709 for 720p and higher while others
> > set V4L2_COLORSPACE_REC709 for anything higher than 576p. Newers drivers
> > use the latter and that also matches what user-space multimedia programs
> > do (i.e: GStreamer), so change the driver logic to be aligned with this.
> >
> > Also, check for the resolution in G_FMT instead unconditionally setting
> > the V4L2_COLORSPACE_REC709 colorspace.
> >
> > Signed-off-by: Javier Martinez Canillas <javier@xxxxxxxxxxxxxxx>
> > Reviewed-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
> >
> > Signed-off-by: Thibault Saunier <thibault.saunier@xxxxxxxxxxxxxxx>
> > ---
> >
> > Changes in v3:
> > - Do not check values in the g_fmt functions as Andrzej explained in previous review
> > - Added 'Reviewed-by: Andrzej Hajda <a.hajda@xxxxxxxxxxx>'
> >
> > Changes in v2: None
> >
> >   drivers/media/platform/exynos-gsc/gsc-core.c | 8 ++++++--
> >   1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/media/platform/exynos-gsc/gsc-core.c b/drivers/media/platform/exynos-gsc/gsc-core.c
> > index 59a634201830..db7d9883861b 100644
> > --- a/drivers/media/platform/exynos-gsc/gsc-core.c
> > +++ b/drivers/media/platform/exynos-gsc/gsc-core.c
> > @@ -472,7 +472,7 @@ int gsc_try_fmt_mplane(struct gsc_ctx *ctx, struct v4l2_format *f)
> >   
> >   	pix_mp->num_planes = fmt->num_planes;
> >   
> > -	if (pix_mp->width >= 1280) /* HD */
> > +	if (pix_mp->width > 720 && pix_mp->height > 576) /* HD */
> >   		pix_mp->colorspace = V4L2_COLORSPACE_REC709;
> >   	else /* SD */
> >   		pix_mp->colorspace = V4L2_COLORSPACE_SMPTE170M;
> > @@ -519,9 +519,13 @@ int gsc_g_fmt_mplane(struct gsc_ctx *ctx, struct v4l2_format *f)
> >   	pix_mp->height		= frame->f_height;
> >   	pix_mp->field		= V4L2_FIELD_NONE;
> >   	pix_mp->pixelformat	= frame->fmt->pixelformat;
> > -	pix_mp->colorspace	= V4L2_COLORSPACE_REC709;
> >   	pix_mp->num_planes	= frame->fmt->num_planes;
> >   
> > +	if (pix_mp->width > 720 && pix_mp->height > 576) /* HD */
> > +		pix_mp->colorspace = V4L2_COLORSPACE_REC709;
> > +	else /* SD */
> > +		pix_mp->colorspace = V4L2_COLORSPACE_SMPTE170M;
> > +
> >   	for (i = 0; i < pix_mp->num_planes; ++i) {
> >   		pix_mp->plane_fmt[i].bytesperline = (frame->f_width *
> >   			frame->fmt->depth[i]) / 8;
> This is a mem2mem device, right? In the case of mem2mem devices the driver should never
> set the colorspace, instead it just copies it from what the application provides (the
> video output side) to the capture side.
>
> After all, you are just scaling here so the input and output colorspaces are
> exactly the same, and the scaler doesn't care what the colorspace is.

This device also does color conversion so I think it matters here, am I 
misunderstanding something?
Also, is that comment only for the try_fmt part as it looks like in 
g_fmt the driver should fill up the structure
with its values?

Thanks for you review.

Regards,

Thibault Saunier
> Regards,
>
> 	Hans