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

   1 From d66098625b057d12fcffdb07a6f2d462e0e2495d Mon Sep 17 00:00:00 2001
   2 From: Dave Stevenson <dave.stevenson@raspberrypi.com>
   3 Date: Tue, 4 Jan 2022 14:46:01 +0000
   4 Subject: [PATCH] media: i2c: ov9281: Increase diff between VTS and max
   5  exposure
   6
   7 The driver did allow the exposure to go up to VTS - 4 lines,
   8 but this would produce a visible line on 1280x800, and a stall of
   9 the sensor at 640x480.
  10
  11 Whilst it appears to work with a difference of 5, the datasheet states
  12 there should be at least 25 lines difference between VTS and exposure,
  13 so use that value.
  14
  15 Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
  16 ---
  17  drivers/media/i2c/ov9281.c | 11 ++++++++---
  18  1 file changed, 8 insertions(+), 3 deletions(-)
  19
  20 --- a/drivers/media/i2c/ov9281.c
  21 +++ b/drivers/media/i2c/ov9281.c
  22 @@ -52,7 +52,11 @@
  23  #define OV9281_REG_EXPOSURE            0x3500
  24  #define        OV9281_EXPOSURE_MIN             4
  25  #define        OV9281_EXPOSURE_STEP            1
  26 -#define OV9281_VTS_MAX                 0x7fff
  27 +/*
  28 + * Number of lines less than frame length (VTS) that exposure must be.
  29 + * Datasheet states 25, although empirically 5 appears to work.
  30 + */
  31 +#define OV9281_EXPOSURE_OFFSET         25
  32
  33  #define OV9281_REG_GAIN_H              0x3508
  34  #define OV9281_REG_GAIN_L              0x3509
  35 @@ -69,6 +73,7 @@
  36  #define OV9281_TEST_PATTERN_DISABLE    0x0
  37
  38  #define OV9281_REG_VTS                 0x380e
  39 +#define OV9281_VTS_MAX                 0x7fff
  40
  41  /*
  42   * OV9281 native and active pixel array size.
  43 @@ -967,7 +972,7 @@ static int ov9281_set_ctrl(struct v4l2_c
  44         switch (ctrl->id) {
  45         case V4L2_CID_VBLANK:
  46                 /* Update max exposure while meeting expected vblanking */
  47 -               max = ov9281->cur_mode->height + ctrl->val - 4;
  48 +               max = ov9281->cur_mode->height + ctrl->val - OV9281_EXPOSURE_OFFSET;
  49                 __v4l2_ctrl_modify_range(ov9281->exposure,
  50                                          ov9281->exposure->minimum, max,
  51                                          ov9281->exposure->step,
  52 @@ -1062,7 +1067,7 @@ static int ov9281_initialize_controls(st
  53                                            OV9281_VTS_MAX - mode->height, 1,
  54                                            vblank_def);
  55
  56 -       exposure_max = mode->vts_def - 4;
  57 +       exposure_max = mode->vts_def - OV9281_EXPOSURE_OFFSET;
  58         ov9281->exposure = v4l2_ctrl_new_std(handler, &ov9281_ctrl_ops,
  59                                              V4L2_CID_EXPOSURE,
  60                                              OV9281_EXPOSURE_MIN, exposure_max,