[PATCH 4.19 072/421] media: imx-csi: Skip first few frames from a BT.656 source

Greg Kroah-Hartman
2021-07-19T16:07:58Z

From: Steve Longerbeam <slongerbeam@gmail.com>

[ Upstream commit e198be37e52551bb863d07d2edc535d0932a3c4f ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 0f8fdc347091..c7df0ffb3510 100644
--- a/drivers/staging/media/imx/imx-media-csi.c
+++ b/drivers/staging/media/imx/imx-media-csi.c
@@ -730,9 +730,10 @@ 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 */
@@ -741,6 +742,17 @@ 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)
--
2.30.2