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

Andy Shevchenko
2022-07-26T12:06:01Z

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