On Fri, Aug 07, 2015 at 11:50:04PM +0800, Feng Tang wrote: > On Fri, Aug 07, 2015 at 04:48:28PM +0200, Michal Nazarewicz wrote: > > On Fri, Aug 07 2015, Feng Tang wrote: > > > As I described above, the dummy struct device is only needed for > > > dma request, its lifetime is align with the cma_heap itself. > > > > Again, this is from perspective of someone who is unfamiliar with ION, > > but perhaps a viable solution is to bypass DMA API and just call > > cma_alloc directly? > > For ion cma heap, the buffer allocation func ion_cma_allocate() will > call dma_alloc_coherent(dev, ...). And dma_alloc_coherent() is > implemented by each architeture(arm/m68k/x86 etc), and many Arch's > implementation doesn't use cma, but use alloc_pages() like APIs. > So I'm afraid we can't direcly call cma_alloc directly here.
Ick. But using a "fake" struct device here, for no real reason, makes me very nervous that you are going to hit a codepath somewhere that assumes this is a "real" struct device and tries to do something with it (dev_printk(), look up what bus it is on, change the name of it, etc.) Trying to fake out the subsystem in this manner is a sign that something is really wrong here. Please either make this a real device, or fix up the api to not need this type of thing. thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
