On Thu, Jun 13, 2024 at 11:48 AM Dan Carpenter dan.carpenter@linaro.org wrote:

On Wed, Jun 12, 2024 at 06:05:54PM +0000, Joy Chakraborty wrote:

...

Read callbacks registered with nvmem core expect 0 to be returned on success and a negative value to be returned on failure.

abx80x_nvmem_xfer() on read calls i2c_smbus_read_i2c_block_data() which returns the number of bytes read on success as per its api description, this return value is handled as an error and returned to nvmem even on success.

Fix to handle all possible values that would be returned by i2c_smbus_read_i2c_block_data().

Fixes: e90ff8ede777 ("rtc: abx80x: Add nvmem support") Cc: stable@vger.kernel.org Signed-off-by: Joy Chakraborty joychakr@google.com

---

drivers/rtc/rtc-abx80x.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-abx80x.c b/drivers/rtc/rtc-abx80x.c index fde2b8054c2e..0f5847d1ca2a 100644 --- a/drivers/rtc/rtc-abx80x.c +++ b/drivers/rtc/rtc-abx80x.c @@ -711,9 +711,16 @@ static int abx80x_nvmem_xfer(struct abx80x_priv *priv, unsigned int offset, else ret = i2c_smbus_read_i2c_block_data(priv->client, reg, len, val);

•         if (ret)
  

•         if (ret < 0)
                  return ret;
  
  

•         if (!write) {
  

•                 if (ret)
  

•                         len = ret;
  

•                 else
  

•                         return -EIO;
  

•         }
  

I guess this is the conservative approach. Ie. Don't break things which aren't already broken. But I suspect the correct approach is to say:

    if (ret != len)
            return -EIO;

Ah well. Being conservative is good. It probably doesn't ever happen in real life so it probably doesn't matter either way.

I don't really like the if (write) follow by and if (!write)... It would add more lines, but improve readability if we just duplicate the code a big:

    if (write) {
            ret = write();
            if (ret)
                    return ret;
    } else {
            ret = read();
            if (ret <= 0)
                    return ret ?: -EIO;
            len = ret;
    }

Sure, I'll do this in a follow up patch.

Thanks Joy

regards, dan carpenter