[PATCH v2 6/8] media: i2c: ov9282: recalculate strobe span on HBLANK change

[Richard Leitner <richard.leitner@linux.dev>]

When HBLANK changes the line time changes. This means the time base for
the strobe duration calculation changed. This results in the v4l2
strobe_duration control value and the strobe_span register value being
out of sync.

Fix this by recalculating the strobe_span register value on HBLANK
writes using the currently configured strobe_duration. This results in
the strobe_duration configured by userspace being kept, but the
underlying register value being changed. To ensure the values are
applied on the same frame guard the writes with OV9282_REG_HOLD.

Fixes: 84ec7597ae1af ("media: i2c: ov9282: add strobe_duration v4l2 control")
Cc: stable@vger.kernel.org
Signed-off-by: Richard Leitner <richard.leitner@linux.dev>
---
 drivers/media/i2c/ov9282.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/media/i2c/ov9282.c b/drivers/media/i2c/ov9282.c
index b48c959b9c908..5114fbf28a26c 100644
--- a/drivers/media/i2c/ov9282.c
+++ b/drivers/media/i2c/ov9282.c
@@ -625,6 +625,7 @@ static int ov9282_set_ctrl(struct v4l2_ctrl *ctrl)
 	u32 exposure;
 	u32 lpfr;
 	int ret;
+	int ret_hold;
 
 	switch (ctrl->id) {
 	case V4L2_CID_VBLANK:
@@ -677,8 +678,14 @@ static int ov9282_set_ctrl(struct v4l2_ctrl *ctrl)
 				      OV9282_FLIP_BIT, ctrl->val ? OV9282_FLIP_BIT : 0, NULL);
 		break;
 	case V4L2_CID_HBLANK:
-		ret = cci_write(ov9282->regmap, OV9282_REG_TIMING_HTS,
-				(ctrl->val + ov9282->cur_mode->width) >> 1, NULL);
+		ret = cci_write(ov9282->regmap, OV9282_REG_HOLD, 0x01, NULL);
+		cci_write(ov9282->regmap, OV9282_REG_TIMING_HTS,
+			  (ctrl->val + ov9282->cur_mode->width) >> 1, &ret);
+		cci_write(ov9282->regmap, OV9282_REG_STROBE_FRAME_SPAN,
+			  ov9282_us_to_lines(ov9282, ov9282->flash_duration->cur.val),
+			  &ret);
+		ret_hold = cci_write(ov9282->regmap, OV9282_REG_HOLD, 0, NULL);
+		ret = ret ? ret : ret_hold;
 		break;
 	case V4L2_CID_FLASH_STROBE_OE:
 		ret = cci_update_bits(ov9282->regmap, OV9282_REG_OUTPUT_ENABLE6,

-- 
2.53.0