Mailing List Archive

From: Dave Stevenson <dave.stevenson@raspberrypi.com>

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>
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
---
drivers/media/i2c/imx258.c | 25 +++++++++++++++++++++++--
1 file changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/media/i2c/imx258.c b/drivers/media/i2c/imx258.c
index c65b9aad3b0a..1f5fb980cfbe 100644
--- a/drivers/media/i2c/imx258.c
+++ b/drivers/media/i2c/imx258.c
@@ -37,10 +37,11 @@

/* 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)

/* Analog gain control */
#define IMX258_REG_ANALOG_GAIN 0x0204
@@ -371,7 +372,7 @@ static const struct imx258_reg mode_common_regs[] = {
{ 0x303A, 0x00 },
{ 0x303B, 0x10 },
{ 0x300D, 0x00 },
- { 0x0350, 0x01 },
+ { 0x0350, 0x00 },
{ 0x0204, 0x00 },
{ 0x0205, 0x00 },
{ 0x020E, 0x01 },
@@ -741,6 +742,19 @@ static int imx258_update_digital_gain(struct imx258 *imx258, u32 len, u32 val)
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 =
@@ -748,6 +762,13 @@ static int imx258_set_ctrl(struct v4l2_ctrl *ctrl)
struct i2c_client *client = v4l2_get_subdevdata(&imx258->sd);
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
--
2.42.0