target/linux/bcm27xx/patches-5.4/950-0874-media-i2c-ov9281-Read-chip-ID-via-2-reads.patch

   1 From 5c6b7b60d7d607b59b4208e758180d4f93be8788 Mon Sep 17 00:00:00 2001
   2 From: Dave Stevenson <dave.stevenson@raspberrypi.com>
   3 Date: Mon, 6 Jul 2020 17:51:32 +0100
   4 Subject: [PATCH] media: i2c: ov9281: Read chip ID via 2 reads
   5
   6 Vision Components have made an OV9281 module which blocks reading
   7 back the majority of registers to comply with NDAs, and in doing
   8 so doesn't allow auto-increment register reading as used when
   9 reading the chip ID.
  10
  11 Use two reads and manually combine the results.
  12
  13 Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
  14 ---
  15  drivers/media/i2c/ov9281.c | 14 +++++++++-----
  16  1 file changed, 9 insertions(+), 5 deletions(-)
  17
  18 --- a/drivers/media/i2c/ov9281.c
  19 +++ b/drivers/media/i2c/ov9281.c
  20 @@ -904,13 +904,17 @@ static int ov9281_check_sensor_id(struct
  21                                   struct i2c_client *client)
  22  {
  23         struct device *dev = &ov9281->client->dev;
  24 -       u32 id = 0;
  25 +       u32 id = 0, id_msb;
  26         int ret;
  27
  28 -       ret = ov9281_read_reg(client, OV9281_REG_CHIP_ID,
  29 -                             OV9281_REG_VALUE_16BIT, &id);
  30 -       if (id != CHIP_ID) {
  31 -               dev_err(dev, "Unexpected sensor id(%06x), ret(%d)\n", id, ret);
  32 +       ret = ov9281_read_reg(client, OV9281_REG_CHIP_ID + 1,
  33 +                             OV9281_REG_VALUE_08BIT, &id);
  34 +       if (!ret)
  35 +               ret = ov9281_read_reg(client, OV9281_REG_CHIP_ID,
  36 +                                     OV9281_REG_VALUE_08BIT, &id_msb);
  37 +       id |= (id_msb << 8);
  38 +       if (ret || id != CHIP_ID) {
  39 +               dev_err(dev, "Unexpected sensor id(%04x), ret(%d)\n", id, ret);
  40                 return -ENODEV;
  41         }
  42