On Mon, 2015-01-05 at 19:50 +0200, Daniel Baluta wrote: > On Mon, Jan 5, 2015 at 6:42 PM, Joe Perches <joe@xxxxxxxxxxx> wrote: > > On Mon, 2015-01-05 at 16:20 +0200, Daniel Baluta wrote: > >> On Mon, Jan 5, 2015 at 3:09 PM, Joe Perches <joe@xxxxxxxxxxx> wrote: > >> > On Mon, 2015-01-05 at 12:51 +0200, Daniel Baluta wrote: > >> >> On Thu, Jan 1, 2015 at 2:10 AM, Kevin Tsai <ktsai@xxxxxxxxxxxxxxxx> wrote: > >> >> > CM3232 is an advanced ambient light sensor with I2C protocol interface. > >> >> > The I2C slave address is internally hardwired as 0x10 (7-bit). Writing > >> >> > to configure register is byte mode, but reading ALS register requests to > >> >> > use word mode for 16-bit resolution. > > [] > >> >> You could directly return i2c_smbus_write_byte_data(..). > >> > > >> > Sometimes it's better to return a specific value > >> > for the error instead of depending on correctness > >> > of all the indirect functions in the call chain. > >> > > >> > In this case, all the smbus_xfer functions must > >> > return 0 on success. Do they? > >> > >> Yes. > >> > >> http://lxr.free-electrons.com/source/drivers/i2c/i2c-core.c#L2845 > > > > This doesn't show that adapter->algo->smbus_xfer() > > returns 0, you have to look at the code for that > > indirectly called function. > > I based my answer on the comment at the top of the function: > > 2845 * This executes an SMBus protocol operation, and returns a negative > 2846 * errno code else zero on success. Sure, but comments and code often differ and the implementation of any of those smbus_xfer functions could return a positive value like the byte value or the number of bytes written instead of 0. For correctness, you'd have to inspect them all. If some new future smbus_xfer function was written incorrectly, the return value from this function could now be positive. cheers, Joe -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
