Am 26.06.2013 12:01, schrieb Chen Gang: > On 06/26/2013 05:48 PM, Geert Uytterhoeven wrote: >> On Wed, Jun 26, 2013 at 11:38 AM, Richard Weinberger <richard@xxxxxx> wrote: >>>>>> Since the API itself already contents the meaning: "return NULL means >>>>>> the arch has no related io memory", >> No, NULL means it could not map the I/O memory. >> > > "it could not map the I/O memory" includes "has no related io memory". > So it is enough for our case. > >>>>>> Why not define a generic dummy one in "include/asm-generic/io.h" instead >>>>>> of "HAS_IOMEM" (which has already spread many various places, and also, >>>>>> most of new drivers have to know about it). >>>>>> >>>>>> e.g: in "include/asm-generic/io.h", if "CONFIG_HAS_IOMEM=n", define a >>>>>> dummy ioremap() which return NULL ... (also need consider more details). >>>> >>>> Because we don't even want to build these drivers and not make them fail while >>>> executing io memory related functions. >> Indeed, it doesn't make sense to build drivers that cannot work. >> And they may fail in a very bad way. > > That is our 'platform' guys feeling, not the 'module' guys, as > 'platform' guys, it is better to provide the choice to 'module' guys, > and let them decide by themselves, not forced by us. FYI, this is my last reply to this thread. As Geert and I said, drivers which need io memory have to depend on HAS_IOMEM=y. If an arch does not have io memory these drivers cannot work and therefore we don't want them built. Over and out, //richard -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
