git.openwrt.org Git - openwrt/staging/neocturne.git/blob

   1 From 0633c60ff1ed5897d8996c5683ea07a5d345e660 Mon Sep 17 00:00:00 2001
   2 From: Naushir Patuck <naush@raspberrypi.com>
   3 Date: Wed, 10 Feb 2021 10:50:32 +0000
   4 Subject: [PATCH] media: i2c: imx477: Add very long exposure control to
   5  the driver
   6
   7 Add support for very long exposures by using the exposure multiplier
   8 register. Userland does not need to pass any additional controls to
   9 enable long exposures, it simply requests a larger vblank to extend the
  10 exposure control range appropriately.
  11
  12 Currently, since hblank is fixed, a maximum of approximately 124 seconds
  13 of exposure time can be used. In a future change, hblank could also be
  14 controlled in userland to give over 200 seconds of exposure time.
  15
  16 Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
  17 ---
  18  drivers/media/i2c/imx477.c | 47 +++++++++++++++++++++++++++++++++-----
  19  1 file changed, 41 insertions(+), 6 deletions(-)
  20
  21 --- a/drivers/media/i2c/imx477.c
  22 +++ b/drivers/media/i2c/imx477.c
  23 @@ -44,6 +44,10 @@
  24  #define IMX477_REG_FRAME_LENGTH                0x0340
  25  #define IMX477_FRAME_LENGTH_MAX                0xffdc
  26
  27 +/* Long exposure multiplier */
  28 +#define IMX477_LONG_EXP_SHIFT_MAX      7
  29 +#define IMX477_LONG_EXP_SHIFT_REG      0x3100
  30 +
  31  /* Exposure control */
  32  #define IMX477_REG_EXPOSURE            0x0202
  33  #define IMX477_EXPOSURE_OFFSET         22
  34 @@ -1097,6 +1101,9 @@ struct imx477 {
  35
  36         /* Rewrite common registers on stream on? */
  37         bool common_regs_written;
  38 +
  39 +       /* Current long exposure factor in use. Set through V4L2_CID_VBLANK */
  40 +       unsigned int long_exp_shift;
  41  };
  42
  43  static inline struct imx477 *to_imx477(struct v4l2_subdev *_sd)
  44 @@ -1285,13 +1292,33 @@ static void imx477_adjust_exposure_range
  45
  46         /* Honour the VBLANK limits when setting exposure. */
  47         exposure_max = imx477->mode->height + imx477->vblank->val -
  48 -                                               IMX477_EXPOSURE_OFFSET;
  49 +                      (IMX477_EXPOSURE_OFFSET << imx477->long_exp_shift);
  50         exposure_def = min(exposure_max, imx477->exposure->val);
  51         __v4l2_ctrl_modify_range(imx477->exposure, imx477->exposure->minimum,
  52                                  exposure_max, imx477->exposure->step,
  53                                  exposure_def);
  54  }
  55
  56 +static int imx477_set_frame_length(struct imx477 *imx477, unsigned int val)
  57 +{
  58 +       int ret = 0;
  59 +
  60 +       imx477->long_exp_shift = 0;
  61 +
  62 +       while (val > IMX477_FRAME_LENGTH_MAX) {
  63 +               imx477->long_exp_shift++;
  64 +               val >>= 1;
  65 +       }
  66 +
  67 +       ret = imx477_write_reg(imx477, IMX477_REG_FRAME_LENGTH,
  68 +                              IMX477_REG_VALUE_16BIT, val);
  69 +       if (ret)
  70 +               return ret;
  71 +
  72 +       return imx477_write_reg(imx477, IMX477_LONG_EXP_SHIFT_REG,
  73 +                               IMX477_REG_VALUE_08BIT, imx477->long_exp_shift);
  74 +}
  75 +
  76  static int imx477_set_ctrl(struct v4l2_ctrl *ctrl)
  77  {
  78         struct imx477 *imx477 =
  79 @@ -1299,6 +1326,10 @@ static int imx477_set_ctrl(struct v4l2_c
  80         struct i2c_client *client = v4l2_get_subdevdata(&imx477->sd);
  81         int ret = 0;
  82
  83 +       /*
  84 +        * The VBLANK control may change the limits of usable exposure, so check
  85 +        * and adjust if necessary.
  86 +        */
  87         if (ctrl->id == V4L2_CID_VBLANK)
  88                 imx477_adjust_exposure_range(imx477, ctrl);
  89
  90 @@ -1316,7 +1347,8 @@ static int imx477_set_ctrl(struct v4l2_c
  91                 break;
  92         case V4L2_CID_EXPOSURE:
  93                 ret = imx477_write_reg(imx477, IMX477_REG_EXPOSURE,
  94 -                                      IMX477_REG_VALUE_16BIT, ctrl->val);
  95 +                                      IMX477_REG_VALUE_16BIT, ctrl->val >>
  96 +                                                       imx477->long_exp_shift);
  97                 break;
  98         case V4L2_CID_DIGITAL_GAIN:
  99                 ret = imx477_write_reg(imx477, IMX477_REG_DIGITAL_GAIN,
 100 @@ -1350,9 +1382,8 @@ static int imx477_set_ctrl(struct v4l2_c
 101                                        imx477->vflip->val << 1);
 102                 break;
 103         case V4L2_CID_VBLANK:
 104 -               ret = imx477_write_reg(imx477, IMX477_REG_FRAME_LENGTH,
 105 -                                      IMX477_REG_VALUE_16BIT,
 106 -                                      imx477->mode->height + ctrl->val);
 107 +               ret = imx477_set_frame_length(imx477,
 108 +                                             imx477->mode->height + ctrl->val);
 109                 break;
 110         default:
 111                 dev_info(&client->dev,
 112 @@ -1521,9 +1552,13 @@ static void imx477_set_framing_limits(st
 113         frm_length_default =
 114                      imx477_get_frame_length(mode, &mode->timeperframe_default);
 115
 116 +       /* Default to no long exposure multiplier. */
 117 +       imx477->long_exp_shift = 0;
 118 +
 119         /* Update limits and set FPS to default */
 120         __v4l2_ctrl_modify_range(imx477->vblank, frm_length_min - mode->height,
 121 -                                IMX477_FRAME_LENGTH_MAX - mode->height,
 122 +                                ((1 << IMX477_LONG_EXP_SHIFT_MAX) *
 123 +                                       IMX477_FRAME_LENGTH_MAX) - mode->height,
 124                                  1, frm_length_default - mode->height);
 125
 126         /* Setting this will adjust the exposure limits as well. */