RE: [PATCH v1 2/8] media: ov2740: Replace voodoo coding with understandle flow

Cao, Bingbu
2022-07-27T09:52:16Z

Andy,

Thanks for your patch.

Although I am not familiar with the voodoo programming, it looks
good for me.

Reviewed-by: Bingbu Cao <bingbu.cao@intel.com>

________________________
BRs,
Bingbu Cao

> -----Original Message-----
> From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Sent: Tuesday, July 26, 2022 8:06 PM
> To: Andy Shevchenko <andriy.shevchenko@linux.intel.com>; linux-
> media@vger.kernel.org; linux-kernel@vger.kernel.org
> Cc: Qiu, Tian Shu <tian.shu.qiu@intel.com>; Tu, ShawnX
> <shawnx.tu@intel.com>; Cao, Bingbu <bingbu.cao@intel.com>; Mauro Carvalho
> Chehab <mchehab@kernel.org>
> Subject: [PATCH v1 2/8] media: ov2740: Replace voodoo coding with
> understandle flow
>
> Besides not being understandable at the first glance, the code might
> provoke a compiler or a static analyser tool to warn about out-of-bound
> access (when len == 0).
>
> Replace it with clear flow an understandable intention.
>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
> drivers/media/i2c/ov2740.c | 28 +++++++++++++++++++++++-----
> 1 file changed, 23 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/media/i2c/ov2740.c b/drivers/media/i2c/ov2740.c index
> c975db1bbe8c..81c0ab220339 100644
> --- a/drivers/media/i2c/ov2740.c
> +++ b/drivers/media/i2c/ov2740.c
> @@ -377,10 +377,10 @@ static int ov2740_read_reg(struct ov2740 *ov2740,
> u16 reg, u16 len, u32 *val)
> struct i2c_client *client = v4l2_get_subdevdata(&ov2740->sd);
> struct i2c_msg msgs[2];
> u8 addr_buf[2];
> - u8 data_buf[4] = {0};
> + u8 data_buf[4];
> int ret = 0;
>
> - if (len > sizeof(data_buf))
> + if (len > 4)
> return -EINVAL;
>
> put_unaligned_be16(reg, addr_buf);
> @@ -391,13 +391,22 @@ static int ov2740_read_reg(struct ov2740 *ov2740,
> u16 reg, u16 len, u32 *val)
> msgs[1].addr = client->addr;
> msgs[1].flags = I2C_M_RD;
> msgs[1].len = len;
> - msgs[1].buf = &data_buf[sizeof(data_buf) - len];
> + msgs[1].buf = data_buf;
>
> ret = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
> if (ret != ARRAY_SIZE(msgs))
> return ret < 0 ? ret : -EIO;
>
> - *val = get_unaligned_be32(data_buf);
> + if (len == 4)
> + *val = get_unaligned_be32(data_buf);
> + else if (len == 3)
> + *val = get_unaligned_be24(data_buf);
> + else if (len == 2)
> + *val = get_unaligned_be16(data_buf);
> + else if (len == 1)
> + *val = data_buf[0];
> + else
> + return -EINVAL;
>
> return 0;
> }
> @@ -412,7 +421,16 @@ static int ov2740_write_reg(struct ov2740 *ov2740,
> u16 reg, u16 len, u32 val)
> return -EINVAL;
>
> put_unaligned_be16(reg, buf);
> - put_unaligned_be32(val << 8 * (4 - len), buf + 2);
> + if (len == 4)
> + put_unaligned_be32(val, buf + 2);
> + else if (len == 3)
> + put_unaligned_be24(val, buf + 2);
> + else if (len == 2)
> + put_unaligned_be16(val, buf + 2);
> + else if (len == 1)
> + buf[2] = val;
> + else
> + return -EINVAL;
>
> ret = i2c_master_send(client, buf, len + 2);
> if (ret != len + 2)
> --
> 2.35.1