[PATCH v2 2/2] media: i2c: imx283: Fix hang when going from large to small resolution

[Jai Luthra]

When switching between modes (e.g. full resolution to binned),
standby_cancel() previously cleared XMSTA (starting master mode data
output) before the new mode's MDSEL, crop, and timing registers were
programmed in start_streaming(). This caused the sensor to briefly
output MIPI data using the previous mode's configuration.

On receivers like imx-mipi-csis, this leads to FIFO overflow errors
when switching from a higher to a lower resolution, as the receiver is
configured for the new smaller frame size but receives stale
full-resolution data.

Fix this by moving the XMSTA and SYNCDRV register writes from
standby_cancel() to the end of start_streaming(), after all mode,
crop, and timing registers have been configured. Also explicitly stop
master mode (XMSTA=1) when stopping the stream, matching the pattern
used by other Sony sensor drivers (imx290, imx415).

Use named macros IMX283_XMSTA_START/STOP instead of raw 0/BIT(0) for
readability.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: ccb4eb4496fa ("media: i2c: Add imx283 camera sensor driver")
Signed-off-by: Jai Luthra <jai.luthra@xxxxxxxxxxxxxxxx>
---
 drivers/media/i2c/imx283.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/drivers/media/i2c/imx283.c b/drivers/media/i2c/imx283.c
index 9b3094a57873c6e8ff8c41d058ea3b0012642cac..1be6164c2d15524690b738aa725a6708e84487d0 100644
--- a/drivers/media/i2c/imx283.c
+++ b/drivers/media/i2c/imx283.c
@@ -129,7 +129,8 @@
 
 /* Master Mode Operation Control */
 #define IMX283_REG_XMSTA		CCI_REG8(0x3105)
-#define   IMX283_XMSTA			BIT(0)
+#define   IMX283_XMSTA_START		0
+#define   IMX283_XMSTA_STOP		BIT(0)
 
 #define IMX283_REG_SYNCDRV		CCI_REG8(0x3107)
 #define   IMX283_SYNCDRV_XHS_XVS	(0xa0 | 0x02)
@@ -1023,8 +1024,6 @@ static int imx283_standby_cancel(struct imx283 *imx283)
 	usleep_range(19000, 20000);
 
 	cci_write(imx283->cci, IMX283_REG_CLAMP, IMX283_CLPSQRST, &ret);
-	cci_write(imx283->cci, IMX283_REG_XMSTA, 0, &ret);
-	cci_write(imx283->cci, IMX283_REG_SYNCDRV, IMX283_SYNCDRV_XHS_XVS, &ret);
 
 	return ret;
 }
@@ -1117,6 +1116,10 @@ static int imx283_start_streaming(struct imx283 *imx283,
 	/* Apply customized values from controls (HMAX/VMAX/SHR) */
 	ret =  __v4l2_ctrl_handler_setup(imx283->sd.ctrl_handler);
 
+	/* Start master mode */
+	cci_write(imx283->cci, IMX283_REG_XMSTA, IMX283_XMSTA_START, &ret);
+	cci_write(imx283->cci, IMX283_REG_SYNCDRV, IMX283_SYNCDRV_XHS_XVS, &ret);
+
 	return ret;
 }
 
@@ -1153,12 +1156,14 @@ static int imx283_disable_streams(struct v4l2_subdev *sd,
 				  u64 streams_mask)
 {
 	struct imx283 *imx283 = to_imx283(sd);
-	int ret;
+	int ret = 0;
 
 	if (pad != IMAGE_PAD)
 		return -EINVAL;
 
-	ret = cci_write(imx283->cci, IMX283_REG_STANDBY, IMX283_STANDBY, NULL);
+	cci_write(imx283->cci, IMX283_REG_XMSTA, IMX283_XMSTA_STOP, &ret);
+	cci_write(imx283->cci, IMX283_REG_STANDBY, IMX283_STANDBY, &ret);
+
 	if (ret)
 		dev_err(imx283->dev, "Failed to stop stream\n");
 

-- 
2.53.0