Re: [PATCH v3 21/24] media: imx: Add MIPI CSI-2 Receiver subdev driver

[Russell King - ARM Linux]

On Fri, Jan 06, 2017 at 06:11:39PM -0800, Steve Longerbeam wrote:
> +static int imxcsi2_get_fmt(struct v4l2_subdev *sd,
> +			   struct v4l2_subdev_pad_config *cfg,
> +			   struct v4l2_subdev_format *sdformat)
> +{
> +	struct imxcsi2_dev *csi2 = sd_to_dev(sd);
> +
> +	sdformat->format = csi2->format_mbus;
> +
> +	return 0;
> +}

Hi Steve,

This isn't correct, and I suspect the other get_fmt implementations are
the same - I've just checked imx-csi.c, and that also appears to have
the same issue.

When get_fmt() is called with sdformat->which == V4L2_SUBDEV_FORMAT_TRY,
you need to return the try format rather than the current format.  See
the second paragraph of Documentation/media/uapi/v4l/dev-subdev.rst's
"Format Negotiation" section, where it talks about using
V4L2_SUBDEV_FORMAT_TRY with both VIDIOC_SUBDEV_G_FMT and
VIDIOC_SUBDEV_S_FMT.

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