On Monday 09 January 2012, Uwe Kleine-König wrote: > On Fri, Dec 23, 2011 at 09:44:28PM +0100, Uwe Kleine-König wrote: > > On Fri, Dec 23, 2011 at 10:35:22AM +0000, Arnd Bergmann wrote: > > > On Thursday 22 December 2011, Uwe Kleine-König wrote: > > > > [...] > > > > +config SERIAL_EFM32_USART > > > > + bool "EFM32 USART port." > > > > + depends on ARCH_EFM32 > > > > + select SERIAL_CORE > > [...] > > > I would generally prefer not to make the driver depend on the > > > platform, so we can get better compile time coverage. I think a better > > > set of dependencies would be > > > > > > depends on HAVE_CLK > > > depends on OF > > > default ARCH_EFM32 > > I'd prefer something like: > > > > depends on HAVE_CLK > > depends on ARCH_EFM32 || I_DO_BUILD_COVERAGE_TESTING > > > > This would make it easier for Joe User to pick the right options for his > > kernel (assuming he found out to better keep I_DO_BUILD_COVERAGE_TESTING > > disabled). [...] > > What do you think about this I_DO_BUILD_COVERAGE_TESTING option? It > would allow testers to get all possible options enabled (though there > will never be an EFM32 USART port on a non-EFM32 machine I guess) and > still users and distribution packagers would easily keep the option off > even without cluttering .config and {menu,n,x,whatever}config. Sorry for the late reply. The same topic has been discussed a lot of times. We have different ways to handle this in the kernel, but the way most common way is to use defconfig to decide which drivers to use on a given machine but give the user the freedom to both enable and disable any driver whereever possible, even if that would be a silly thing to do. What we do require normally is that anything that can be enabled is also able to be built without errors. A lot of drivers have dependencies on platform specific header files or other interfaces, so they require that platform to be enabled. For all others I would not make such a restriction and I would always recommend to be specific in the dependencies, e.g depending on HAVE_CLK when you use the clock interfaces, instead of depending on other options that implicitly enable HAVE_CLK. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html