On Tue, Sep 15, 2020 at 10:40:39AM -0400, Thomas Tai wrote: >> +++ b/include/linux/dma-direct.h >> @@ -62,9 +62,6 @@ static inline bool dma_capable(struct device *dev, >> dma_addr_t addr, size_t size, >> { >> dma_addr_t end = addr + size - 1; >> - if (!dev->dma_mask) >> - return false; >> - > > I am concerned that some drivers may rely on this NULL checking. Would you > think we can keep this checking and use the following WARN_ON_ONCE()?
dma_capable is not a helper for drivers, but just for dma-direct and related code. And this patch adds the checks for the three places how we call into the ->map* methods.