linux-kernel - [PATCH 2/3] media: i2c: imx283: Recalculate SHR on blanking changes

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Message-ID: <20250918132753.3154059-3-kieran.bingham@ideasonboard.com>
Date: Thu, 18 Sep 2025 14:27:52 +0100
From: Kieran Bingham <kieran.bingham@...asonboard.com>
To: linux-media@...r.kernel.org
Cc: Kieran Bingham <kieran.bingham@...asonboard.com>,
	Umang Jain <umang.jain@...asonboard.com>,
	Sakari Ailus <sakari.ailus@...ux.intel.com>,
	Mauro Carvalho Chehab <mchehab@...nel.org>,
	linux-kernel@...r.kernel.org (open list)
Subject: [PATCH 2/3] media: i2c: imx283: Recalculate SHR on blanking changes

The exposure control on the imx283 is handled through the SHR register.
This value is calculated based upon the hmax and vmax registers as a
property of the total line and frame length.

Ensure that the SHR is updated whenever the blankings update and adjust
the frame intervals to ensure the correct exposure is configured on the
sensor.

Signed-off-by: Kieran Bingham <kieran.bingham@...asonboard.com>
---
 drivers/media/i2c/imx283.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/media/i2c/imx283.c b/drivers/media/i2c/imx283.c
index 06c4b01868c0..582975ac849f 100644
--- a/drivers/media/i2c/imx283.c
+++ b/drivers/media/i2c/imx283.c
@@ -807,6 +807,11 @@ static int imx283_set_ctrl(struct v4l2_ctrl *ctrl)
 		dev_dbg(imx283->dev, "V4L2_CID_HBLANK : %d  HMAX : %u\n",
 			ctrl->val, imx283->hmax);
 		ret = cci_write(imx283->cci, IMX283_REG_HMAX, imx283->hmax, NULL);
+
+		/* Recompute the SHR based on the new timings */
+		shr = imx283_shr(imx283, mode, imx283->exposure->val);
+		cci_write(imx283->cci, IMX283_REG_SHR, shr, &ret);
+
 		break;
 
 	case V4L2_CID_VBLANK:
@@ -814,6 +819,11 @@ static int imx283_set_ctrl(struct v4l2_ctrl *ctrl)
 		dev_dbg(imx283->dev, "V4L2_CID_VBLANK : %d  VMAX : %u\n",
 			ctrl->val, imx283->vmax);
 		ret = cci_write(imx283->cci, IMX283_REG_VMAX, imx283->vmax, NULL);
+
+		/* Recompute the SHR based on the new timings */
+		shr = imx283_shr(imx283, mode, imx283->exposure->val);
+		cci_write(imx283->cci, IMX283_REG_SHR, shr, &ret);
+
 		break;
 
 	case V4L2_CID_ANALOGUE_GAIN:
-- 
2.50.1