On Fri, Sep 11, 2009 at 09:19, Hennerich, Michael wrote:
> On Friday 11 September 2009, Song, Barry wrote:
> +static int __init ad714x_init(void)
> +{
> +
> + int ret = 0;
> + ret = ad714x_spi_register_driver(&ad714x_spi_driver);
> + if (ret)
> + goto err;
> + ret = ad714x_i2c_add_driver(&ad714x_i2c_driver);
> + if (ret)
> + ad714x_spi_unregister_driver(&ad714x_spi_driver);
> +err:
> + return ret;
> +}
> +
> +static void __exit ad714x_exit(void)
> +{
> + ad714x_spi_unregister_driver(&ad714x_spi_driver);
> + ad714x_i2c_del_driver(&ad714x_i2c_driver);
> +}
>
> This doesn't make much sense!
> Assuming we have two AD714x in a system. One connected by SPI the other
> by I2C.
> Why would I remove the SPI one in case the other I2C fails, or not even
> try the SPI one if the I2C fails?
is this a realistic problem ? we arent talking about failure to probe
the device, we're talking about failure to register the driver as
available. i.e. the only way the module_init step should fail is if
i2c_add_driver() or spi_register_driver() fails. and if either of
those fail, it's most likely a pretty bad situation.
failure to probe/detect/talk to the device are a different issue and a
problem with one interface will not affect the other.
> Who says that a driver can't have two module_init()?
Mr. C Code says it wont work. if ad714x is built as a module and both
I2C and SPI support are enabled, we get:
drivers/input/misc/ad714x.c:1621: error: redefinition of ‘__inittest’
drivers/input/misc/ad714x.c:1492: error: previous definition of
‘__inittest’ was here
these lines correspond to the module_init() macro
linux/init.h says:
/* Each module must use one module_init(). */
#define module_init(initfn) \
static inline initcall_t __inittest(void) \
{ return initfn; } \
int init_module(void) __attribute__((alias(#initfn)));
and indeed, the error makes sense -- you cant have multiple functions
named the same thing (in this case, we'd have two __inittest() and two
init_module())
-mike
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