linux-kernel - [PATCH AUTOSEL 5.4 35/50] media: imx-csi: Skip first few frames from a BT.656 source

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Message-Id: <20210704230938.1490742-35-sashal@kernel.org>
Date:   Sun,  4 Jul 2021 19:09:23 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Steve Longerbeam <slongerbeam@...il.com>,
        Fabio Estevam <festevam@...il.com>,
        Tim Harvey <tharvey@...eworks.com>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Mauro Carvalho Chehab <mchehab+huawei@...nel.org>,
        Sasha Levin <sashal@...nel.org>, linux-media@...r.kernel.org,
        linux-staging@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org
Subject: [PATCH AUTOSEL 5.4 35/50] media: imx-csi: Skip first few frames from a BT.656 source

From: Steve Longerbeam <slongerbeam@...il.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@...il.com>
Signed-off-by: Fabio Estevam <festevam@...il.com>
Reviewed-by: Tim Harvey <tharvey@...eworks.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@...all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.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 367e39f5b382..40b7e60f4a47 100644
--- a/drivers/staging/media/imx/imx-media-csi.c
+++ b/drivers/staging/media/imx/imx-media-csi.c
@@ -753,9 +753,10 @@ 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 */
@@ -764,6 +765,17 @@ 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