On Thursday 03 March 2016 09:17:31 Vinod Koul wrote: > On Wed, Mar 02, 2016 at 04:58:58PM +0100, Arnd Bergmann wrote: > > The sirf dma driver uses #ifdef to check for CONFIG_PM_SLEEP > > for its suspend/resume code but then has no #ifdef for the > > respective runtime PM code, so we get a warning if CONFIG_PM > > is disabled altogether: > > > > drivers/dma/sirf-dma.c:1000:12: error: 'sirfsoc_dma_runtime_resume' defined but not used [-Werror=unused-function] > > > > This removes the existing #ifdef and instead uses __maybe_unused > > annotations for all four functions to let the compiler know it > > can silently drop the function definition. > > Hi Arnd, > > Rather than telling compiler that this maybe used why not add ifdef for it's > suspend/resume as well, what are the demerits of that approach? > As I tried to explain in the cover letter, everyone gets the #ifdef wrong, and the __maybe_unused annotation is harder to get wrong here. This particular driver illustrates that well: sirfsoc_dma_remove() calls sirfsoc_dma_runtime_suspend(), so we must hide the resume function, but not suspend, and that is counterintuitive. Other drivers have other problems, e.g. functions that get called only from within the sections under an #ifdef, and then those need the same #ifdef added, which gets even more complicated when you have both runtime-pm and suspend support. Arnd -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
