media: imx-csi: Skip first few frames from a BT.656 source

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.

[fabio: fixed checkpatch warning and increased the frame skipping to 20]

Signed-off-by: Steve Longerbeam <slongerbeam@gmail.com>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

diff --git a/drivers/staging/media/imx/imx-media-csi.c b/drivers/staging/media/imx/imx-media-csi.c
index d2f1d40..bb1305c 100644 (file)
--- 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)