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SubjectRe: [PATCH 1/1] mfd: twl4030: clarify the return value for read and write
On Mon, Dec 07, 2009 at 01:17:29PM +0100, ext Amit Kucheria wrote:
> Infact, we can just return -EIO so that caller knows for sure that all
> messages were not tranferred. Please consider fixed patch instead.
>
> We should be checking if all the messages were tranferred or not. And return
> -1 for failure. Currently we return success (0) even if none of messages were
> transferred successfully.
>
> Signed-off-by: Amit Kucheria <amit.kucheria@verdurent.com>
> ---
> drivers/mfd/twl4030-core.c | 24 ++++++++++++++++--------
> 1 files changed, 16 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/mfd/twl4030-core.c b/drivers/mfd/twl4030-core.c
> index 56f1de5..3d2c413 100644
> --- a/drivers/mfd/twl4030-core.c
> +++ b/drivers/mfd/twl4030-core.c
> @@ -292,10 +292,14 @@ int twl4030_i2c_write(u8 mod_no, u8 *value, u8 reg, unsigned num_bytes)
> ret = i2c_transfer(twl->client->adapter, twl->xfer_msg, 1);
> mutex_unlock(&twl->xfer_lock);
>
> - /* i2cTransfer returns num messages.translate it pls.. */
> - if (ret >= 0)
> - ret = 0;
> - return ret;
> + /* i2c_transfer returns number of messages transferred */
> + if (ret != 1) {
> + pr_err("%s: i2c_write failed to transfer all messages\n",
> + DRIVER_NAME);
> + return -EIO;

How about reporting the actual error that has occurred and reported by i2c_transfer?
Instead of just masking it as EIO? If i2c_transfer returns something > 0 then EIO should be right.
But if returns and error code, then that error code must be reported to upper layers.

> + } else {
> + return 0;
> + }
> }
> EXPORT_SYMBOL(twl4030_i2c_write);
>
> @@ -344,10 +348,14 @@ int twl4030_i2c_read(u8 mod_no, u8 *value, u8 reg, unsigned num_bytes)
> ret = i2c_transfer(twl->client->adapter, twl->xfer_msg, 2);
> mutex_unlock(&twl->xfer_lock);
>
> - /* i2cTransfer returns num messages.translate it pls.. */
> - if (ret >= 0)
> - ret = 0;
> - return ret;
> + /* i2c_transfer returns number of messages transferred */
> + if (ret != 2) {
> + pr_err("%s: i2c_read failed to transfer all messages\n",
> + DRIVER_NAME);
> + return -EIO;


dito.

> + } else {
> + return 0;
> + }
> }
> EXPORT_SYMBOL(twl4030_i2c_read);
>
> --
> 1.6.3.3
>
> --
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--
Eduardo Valentin


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