[PATCH] [media] imx: csi: retain current field order and colorimetry setting as default

[Hans Verkuil]

Hi Philipp,

Sorry for the very long delay, but I finally had some time to think about this.

On 04/06/2017 03:55 PM, Philipp Zabel wrote:
> If the the field order is set to ANY in set_fmt, choose the currently
> set field order. If the colorspace is set to DEFAULT, choose the current
> colorspace.  If any of xfer_func, ycbcr_enc or quantization are set to
> DEFAULT, either choose the current setting, or the default setting for the
> new colorspace, if non-DEFAULT colorspace was given.
> 
> This allows to let field order and colorimetry settings be propagated
> from upstream by calling media-ctl on the upstream entity source pad,
> and then call media-ctl on the sink pad to manually set the input frame
> interval, without changing the already set field order and colorimetry
> information.
> 
> Signed-off-by: Philipp Zabel <p.zabel at pengutronix.de>
> ---
> This is based on imx-media-staging-md-v14, and it is supposed to allow
> configuring the pipeline with media-ctl like this:
> 
> 1) media-ctl --set-v4l2 "'tc358743 1-000f':0[fmt:UYVY8_1X16/1920x1080]"
> 2) media-ctl --set-v4l2 "'imx6-mipi-csi2':1[fmt:UYVY8_1X16/1920x108]"
> 3) media-ctl --set-v4l2 "'ipu1_csi0_mux':2[fmt:UYVY8_1X16/1920x1080]"
> 4) media-ctl --set-v4l2 "'ipu1_csi0':0[fmt:UYVY8_1X16/1920x1080 at 1/60]"
> 5) media-ctl --set-v4l2 "'ipu1_csi0':2[fmt:AYUV32/1920x1080 at 1/30]"
> 
> Without having step 4) overwrite the colorspace and field order set on
> 'ipu1_csi0':0 by the propagation in step 3).
> ---
>  drivers/staging/media/imx/imx-media-csi.c | 34 +++++++++++++++++++++++++++++++
>  1 file changed, 34 insertions(+)
> 
> diff --git a/drivers/staging/media/imx/imx-media-csi.c b/drivers/staging/media/imx/imx-media-csi.c
> index 64dc454f6b371..d94ce1de2bf05 100644
> --- a/drivers/staging/media/imx/imx-media-csi.c
> +++ b/drivers/staging/media/imx/imx-media-csi.c
> @@ -1325,6 +1325,40 @@ static int csi_set_fmt(struct v4l2_subdev *sd,
>  	csi_try_fmt(priv, sensor, cfg, sdformat, crop, compose, &cc);
>  
>  	fmt = __csi_get_fmt(priv, cfg, sdformat->pad, sdformat->which);
> +
> +	/* Retain current field setting as default */
> +	if (sdformat->format.field == V4L2_FIELD_ANY)
> +		sdformat->format.field = fmt->field;

This is OK.

> +
> +	/* Retain current colorspace setting as default */
> +	if (sdformat->format.colorspace == V4L2_COLORSPACE_DEFAULT) {
> +		sdformat->format.colorspace = fmt->colorspace;
> +		if (sdformat->format.xfer_func == V4L2_XFER_FUNC_DEFAULT)
> +			sdformat->format.xfer_func = fmt->xfer_func;
> +		if (sdformat->format.ycbcr_enc == V4L2_YCBCR_ENC_DEFAULT)
> +			sdformat->format.ycbcr_enc = fmt->ycbcr_enc;
> +		if (sdformat->format.quantization == V4L2_QUANTIZATION_DEFAULT)
> +			sdformat->format.quantization = fmt->quantization;

If sdformat->format.colorspace == V4L2_COLORSPACE_DEFAULT, then you can just copy
all four fields from fmt to sdformat->format. The other three fields are meaningless
when colorspace == V4L2_COLORSPACE_DEFAULT.

> +	} else {
> +		if (sdformat->format.xfer_func == V4L2_XFER_FUNC_DEFAULT) {
> +			sdformat->format.xfer_func =
> +				V4L2_MAP_XFER_FUNC_DEFAULT(
> +						sdformat->format.colorspace);
> +		}
> +		if (sdformat->format.ycbcr_enc == V4L2_YCBCR_ENC_DEFAULT) {
> +			sdformat->format.ycbcr_enc =
> +				V4L2_MAP_YCBCR_ENC_DEFAULT(
> +						sdformat->format.colorspace);
> +		}
> +		if (sdformat->format.quantization == V4L2_QUANTIZATION_DEFAULT) {
> +			sdformat->format.quantization =
> +				V4L2_MAP_QUANTIZATION_DEFAULT(
> +						cc->cs != IPUV3_COLORSPACE_YUV,
> +						sdformat->format.colorspace,
> +						sdformat->format.ycbcr_enc);
> +		}

Is this needed for validation? Currently these fields play no role in the
default link validation. Which I think is actually the right thing to do,
unless the subdev can do actual colorspace conversion.

I would just drop the whole 'else' here.

Actually, wouldn't it be better to always just copy this information from
fmt? This subdev doesn't do any colorspace conversion, it just passes on
this information. I.e., you can't set it in any meaningful way.

Regards,

	Hans

> +	}
> +
>  	*fmt = sdformat->format;
>  
>  	if (sdformat->pad == CSI_SINK_PAD) {
>