On Mon, May 17, 2021 at 7:29 AM Fabio Estevam <festevam@xxxxxxxxx> wrote:
>
> From: Steve Longerbeam <slongerbeam@xxxxxxxxx>
>
> Some BT.656 sensors (e.g. ADV718x) transmit frames with unstable BT.656
> sync codes after initial power on. This confuses the imx CSI,resulting
> in vertical and/or horizontal sync issues. Skip the first 20 frames
> to avoid the unstable sync codes.
>
> Signed-off-by: Steve Longerbeam <slongerbeam@xxxxxxxxx>
> [fabio: fixed checkpatch warning and increased the frame skipping to 20]
> Signed-off-by: Fabio Estevam <festevam@xxxxxxxxx>
> ---
> Changes since v2:
> - Increase 'bad_frames' to 20 as 10 was not enough to avoid
> the problem when using an NTSC camera.
>
> drivers/staging/media/imx/imx-media-csi.c | 14 +++++++++++++-
> 1 file changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/staging/media/imx/imx-media-csi.c b/drivers/staging/media/imx/imx-media-csi.c
> index e3bfd635a89a..6a94fff49bf6 100644
> --- a/drivers/staging/media/imx/imx-media-csi.c
> +++ b/drivers/staging/media/imx/imx-media-csi.c
> @@ -750,9 +750,10 @@ static int csi_setup(struct csi_priv *priv)
>
> static int csi_start(struct csi_priv *priv)
> {
> - struct v4l2_fract *output_fi;
> + struct v4l2_fract *input_fi, *output_fi;
> int ret;
>
> + input_fi = &priv->frame_interval[CSI_SINK_PAD];
> output_fi = &priv->frame_interval[priv->active_output_pad];
>
> /* start upstream */
> @@ -761,6 +762,17 @@ static int csi_start(struct csi_priv *priv)
> if (ret)
> return ret;
>
> + /* Skip first few frames from a BT.656 source */
> + if (priv->upstream_ep.bus_type == V4L2_MBUS_BT656) {
> + u32 delay_usec, bad_frames = 20;
> +
> + delay_usec = DIV_ROUND_UP_ULL((u64)USEC_PER_SEC *
> + input_fi->numerator * bad_frames,
> + input_fi->denominator);
> +
> + usleep_range(delay_usec, delay_usec + 1000);
> + }
> +
> if (priv->dest == IPU_CSI_DEST_IDMAC) {
> ret = csi_idmac_start(priv);
> if (ret)
> --
> 2.25.1
>
Reviewed-By: Tim Harvey <tharvey@xxxxxxxxxxxxx>
