From 757db42ab8daacefb3ef9cda49ad6a5ff65fc494 Mon Sep 17 00:00:00 2001
From: Dave Stevenson <dave.stevenson@raspberrypi.com>
Date: Wed, 16 Jun 2021 17:19:17 +0100
Subject: [PATCH 0452/1085] media: i2c: imx258: Follow normal V4L2 behaviours
 for clipping exposure

V4L2 sensor drivers are expected are expected to clip the supported
exposure range based on the VBLANK configured.
IMX258 wasn't doing that as register 0x350 (FRM_LENGTH_CTL)
switches it to a mode where frame length tracks coarse exposure time.

Disable this mode and clip the range for V4L2_CID_EXPOSURE appropriately
based on V4L2_CID_VBLANK.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---
 drivers/media/i2c/imx258.c | 35 ++++++++++++++++++++++++++++-------
 1 file changed, 28 insertions(+), 7 deletions(-)

--- a/drivers/media/i2c/imx258.c
+++ b/drivers/media/i2c/imx258.c
@@ -32,15 +32,16 @@
 
 #define IMX258_REG_VTS			0x0340
 
-/* HBLANK control - read only */
-#define IMX258_PPL_DEFAULT		5352
-
 /* Exposure control */
 #define IMX258_REG_EXPOSURE		0x0202
+#define IMX258_EXPOSURE_OFFSET		10
 #define IMX258_EXPOSURE_MIN		4
 #define IMX258_EXPOSURE_STEP		1
 #define IMX258_EXPOSURE_DEFAULT		0x640
-#define IMX258_EXPOSURE_MAX		65535
+#define IMX258_EXPOSURE_MAX		(IMX258_VTS_MAX - IMX258_EXPOSURE_OFFSET)
+
+/* HBLANK control - read only */
+#define IMX258_PPL_DEFAULT		5352
 
 /* Analog gain control */
 #define IMX258_REG_ANALOG_GAIN		0x0204
@@ -376,7 +377,7 @@ static const struct imx258_reg mode_4208
 	{ 0x034D, 0x70 },
 	{ 0x034E, 0x0C },
 	{ 0x034F, 0x30 },
-	{ 0x0350, 0x01 },
+	{ 0x0350, 0x00 },
 	{ 0x0204, 0x00 },
 	{ 0x0205, 0x00 },
 	{ 0x020E, 0x01 },
@@ -488,7 +489,7 @@ static const struct imx258_reg mode_2104
 	{ 0x034D, 0x38 },
 	{ 0x034E, 0x06 },
 	{ 0x034F, 0x18 },
-	{ 0x0350, 0x01 },
+	{ 0x0350, 0x00 },
 	{ 0x0204, 0x00 },
 	{ 0x0205, 0x00 },
 	{ 0x020E, 0x01 },
@@ -600,7 +601,7 @@ static const struct imx258_reg mode_1048
 	{ 0x034D, 0x18 },
 	{ 0x034E, 0x03 },
 	{ 0x034F, 0x0C },
-	{ 0x0350, 0x01 },
+	{ 0x0350, 0x00 },
 	{ 0x0204, 0x00 },
 	{ 0x0205, 0x00 },
 	{ 0x020E, 0x01 },
@@ -934,6 +935,19 @@ static int imx258_update_digital_gain(st
 	return 0;
 }
 
+static void imx258_adjust_exposure_range(struct imx258 *imx258)
+{
+	int exposure_max, exposure_def;
+
+	/* Honour the VBLANK limits when setting exposure. */
+	exposure_max = imx258->cur_mode->height + imx258->vblank->val -
+		       IMX258_EXPOSURE_OFFSET;
+	exposure_def = min(exposure_max, imx258->exposure->val);
+	__v4l2_ctrl_modify_range(imx258->exposure, imx258->exposure->minimum,
+				 exposure_max, imx258->exposure->step,
+				 exposure_def);
+}
+
 static int imx258_set_ctrl(struct v4l2_ctrl *ctrl)
 {
 	struct imx258 *imx258 =
@@ -942,6 +956,13 @@ static int imx258_set_ctrl(struct v4l2_c
 	int ret = 0;
 
 	/*
+	 * The VBLANK control may change the limits of usable exposure, so check
+	 * and adjust if necessary.
+	 */
+	if (ctrl->id == V4L2_CID_VBLANK)
+		imx258_adjust_exposure_range(imx258);
+
+	/*
 	 * Applying V4L2 control value only happens
 	 * when power is up for streaming
 	 */