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From 69f1022fc3c155f8cd5cf7dacaf283b1778835f3 Mon Sep 17 00:00:00 2001
From: Naushir Patuck <naush@raspberrypi.com>
Date: Fri, 8 May 2020 09:41:17 +0100
Subject: [PATCH] media: i2c: imx477: Add support for adaptive frame
control
Use V4L2_CID_EXPOSURE_AUTO_PRIORITY to control if the driver should
automatically adjust the sensor frame length based on exposure time,
allowing variable frame rates and longer exposures.
Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
---
drivers/media/i2c/imx477.c | 113 +++++++++++++++++++++++++++++--------
1 file changed, 91 insertions(+), 22 deletions(-)
--- a/drivers/media/i2c/imx477.c
+++ b/drivers/media/i2c/imx477.c
@@ -1082,6 +1082,8 @@ struct imx477 {
struct v4l2_ctrl *hflip;
struct v4l2_ctrl *vblank;
struct v4l2_ctrl *hblank;
+ /* This ctrl allows automatic variable framerate */
+ struct v4l2_ctrl *exposure_auto;
/* Current mode */
const struct imx477_mode *mode;
@@ -1278,6 +1280,72 @@ static int imx477_open(struct v4l2_subde
return 0;
}
+static int imx477_set_exposure(struct imx477 *imx477, unsigned int val)
+{
+ int ret;
+
+ ret = imx477_write_reg(imx477, IMX477_REG_EXPOSURE,
+ IMX477_REG_VALUE_16BIT, val);
+
+ /* Setup the frame length in the case of auto framerate mode. */
+ if (imx477->exposure_auto->val) {
+ unsigned int frame_length, frame_length_max, frame_length_min;
+
+ frame_length_min = imx477->vblank->minimum +
+ imx477->mode->height;
+ frame_length_max = imx477->vblank->maximum +
+ imx477->mode->height;
+ frame_length = max(frame_length_min,
+ val + IMX477_EXPOSURE_OFFSET);
+ frame_length = min(frame_length_max, frame_length);
+ ret += imx477_write_reg(imx477, IMX477_REG_FRAME_LENGTH,
+ IMX477_REG_VALUE_16BIT, frame_length);
+ }
+
+ return ret;
+}
+
+static void imx477_adjust_exposure_range(struct imx477 *imx477,
+ struct v4l2_ctrl *ctrl)
+{
+ int exposure_max, exposure_def;
+
+ if (ctrl->id == V4L2_CID_VBLANK || !ctrl->val) {
+ /*
+ * Either VBLANK has been changed or auto framerate
+ * adjusting has been disabled. Honour the VBLANK limits
+ * when setting exposure.
+ */
+ exposure_max = imx477->mode->height + imx477->vblank->val -
+ IMX477_EXPOSURE_OFFSET;
+
+ if (ctrl->id == V4L2_CID_EXPOSURE_AUTO_PRIORITY) {
+ /*
+ * Allow VBLANK adjustments since the driver is not
+ * handling frame length control automatically.
+ */
+ __v4l2_ctrl_grab(imx477->vblank, false);
+ }
+ } else {
+ /*
+ * Auto framerate adjusting has been enabled. VBLANK
+ * ctrl has been disabled and exposure can ramp up
+ * to the maximum allowable value.
+ */
+ exposure_max = IMX477_EXPOSURE_MAX;
+ /*
+ * Do not allow VBLANK adjustments if the driver is
+ * handling it frame length control automatically.
+ */
+ __v4l2_ctrl_grab(imx477->vblank, true);
+ }
+
+ exposure_def = min(exposure_max, imx477->exposure->val);
+ __v4l2_ctrl_modify_range(imx477->exposure, imx477->exposure->minimum,
+ exposure_max, imx477->exposure->step,
+ exposure_def);
+}
+
static int imx477_set_ctrl(struct v4l2_ctrl *ctrl)
{
struct imx477 *imx477 =
@@ -1285,17 +1353,13 @@ static int imx477_set_ctrl(struct v4l2_c
struct i2c_client *client = v4l2_get_subdevdata(&imx477->sd);
int ret = 0;
- if (ctrl->id == V4L2_CID_VBLANK) {
- int exposure_max, exposure_def;
-
- /* Update max exposure while meeting expected vblanking */
- exposure_max = imx477->mode->height + ctrl->val -
- IMX477_EXPOSURE_OFFSET;
- exposure_def = min(exposure_max, imx477->exposure->val);
- __v4l2_ctrl_modify_range(imx477->exposure,
- imx477->exposure->minimum,
- exposure_max, imx477->exposure->step,
- exposure_def);
+ if (ctrl->id == V4L2_CID_VBLANK ||
+ ctrl->id == V4L2_CID_EXPOSURE_AUTO_PRIORITY) {
+ /*
+ * These controls may change the limits of usable exposure,
+ * so check and adjust if necessary.
+ */
+ imx477_adjust_exposure_range(imx477, ctrl);
}
/*
@@ -1311,8 +1375,14 @@ static int imx477_set_ctrl(struct v4l2_c
IMX477_REG_VALUE_16BIT, ctrl->val);
break;
case V4L2_CID_EXPOSURE:
- ret = imx477_write_reg(imx477, IMX477_REG_EXPOSURE,
- IMX477_REG_VALUE_16BIT, ctrl->val);
+ ret = imx477_set_exposure(imx477, ctrl->val);
+ break;
+ case V4L2_CID_EXPOSURE_AUTO_PRIORITY:
+ /*
+ * imx477_set_exposure() will recalculate the frame length
+ * to adjust the framerate to match the exposure.
+ */
+ ret = imx477_set_exposure(imx477, imx477->exposure->val);
break;
case V4L2_CID_DIGITAL_GAIN:
ret = imx477_write_reg(imx477, IMX477_REG_DIGITAL_GAIN,
@@ -1510,9 +1580,8 @@ unsigned int imx477_get_frame_length(con
static void imx477_set_framing_limits(struct imx477 *imx477)
{
+ unsigned int frm_length_min, frm_length_default, hblank;
const struct imx477_mode *mode = imx477->mode;
- unsigned int frm_length_min, frm_length_default;
- unsigned int exposure_max, exposure_def, hblank;
frm_length_min = imx477_get_frame_length(mode, &mode->timeperframe_min);
frm_length_default =
@@ -1522,15 +1591,10 @@ static void imx477_set_framing_limits(st
__v4l2_ctrl_modify_range(imx477->vblank, frm_length_min - mode->height,
IMX477_FRAME_LENGTH_MAX - mode->height,
1, frm_length_default - mode->height);
+
+ /* Setting this will adjust the exposure limits as well. */
__v4l2_ctrl_s_ctrl(imx477->vblank, frm_length_default - mode->height);
- /* Update max exposure while meeting expected vblanking */
- exposure_max = IMX477_FRAME_LENGTH_MAX - IMX477_EXPOSURE_OFFSET;
- exposure_def = frm_length_default - mode->height -
- IMX477_EXPOSURE_OFFSET;
- __v4l2_ctrl_modify_range(imx477->exposure, imx477->exposure->minimum,
- exposure_max, imx477->exposure->step,
- exposure_def);
/*
* Currently PPL is fixed to the mode specified value, so hblank
* depends on mode->width only, and is not changeable in any
@@ -1939,6 +2003,11 @@ static int imx477_init_controls(struct i
IMX477_DGTL_GAIN_MIN, IMX477_DGTL_GAIN_MAX,
IMX477_DGTL_GAIN_STEP, IMX477_DGTL_GAIN_DEFAULT);
+ imx477->exposure_auto =
+ v4l2_ctrl_new_std(ctrl_hdlr, &imx477_ctrl_ops,
+ V4L2_CID_EXPOSURE_AUTO_PRIORITY,
+ 0, 1, 1, 0);
+
imx477->hflip = v4l2_ctrl_new_std(ctrl_hdlr, &imx477_ctrl_ops,
V4L2_CID_HFLIP, 0, 1, 1, 0);
if (imx477->hflip)
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