On Thu, Dec 10, 2015 at 02:14:49PM +0100, Arnd Bergmann wrote: > The emev2 driver stopped compiling in today's linux-next kernel: > > drivers/i2c/busses/i2c-emev2.c: In function 'em_i2c_slave_irq': > drivers/i2c/busses/i2c-emev2.c:233:23: error: storage size of 'event' isn't known > drivers/i2c/busses/i2c-emev2.c:250:3: error: implicit declaration of function 'i2c_slave_event' [-Werror=implicit-function-declaration] > drivers/i2c/busses/i2c-emev2.c:250:32: error: 'I2C_SLAVE_STOP' undeclared (first use in this function) > > It works again if we enable CONFIG_I2C_SLAVE, but it seems wrong > to add a dependency on that symbol: > > * The symbol is user-selectable, but only one or two (including this > one) bus drivers actually implement it, and it makes no sense > if you don't have one of them. > > * The other driver (R-Car) uses 'select I2C_SLAVE', which seems > reasonable in principle, but we should not do that on user > visible symbols. > > * I2C slave mode could be implemented in a lot of other drivers > as an optional feature, but we shouldn't require enabling it > if we don't use it. > > This changes the two drivers that provide I2C slave mode so they > can again build if the slave mode being disabled. To do this, I > move the definition of i2c_slave_event() and enum i2c_slave_event > out of the #ifdef and instead make the assignment of the reg_slave > and unreg_slave pointers optional in the bus drivers. The functions > implementing the feature are unused in that case, so they get > marked as __maybe_unused in order to still give compile-time > coverage. Thanks a lot! Making this clear and consistent was on my todo-list, unfortunately below some other items. Both drivers have quite orthogonal slave_irq routines. What do you think about grouping this and the reg/unreg-calls together and compile them conditionally on I2C_SLAVE? I think the code savings are worth it.
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