On Fri, Aug 07, 2015 at 04:09:12PM -0700, Laura Abbott wrote: > On 08/07/2015 11:05 AM, Greg Kroah-Hartman wrote: > >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. > > > > I think this issue represents one of the many current issues with Ion. > When the void * == struct dev was added, everything was working off of > board files. We now have devicetree which makes the device association > even more awkward to pull off. Every vendor out there is doing something > different right now so the assertion in the commit text about 'normal' > is not true; existing code has managed to work with the (not super great) > API. > > There is going to be an Ion session at Plumbers in a few weeks. I'd like > to propose holding off on merging anything until after plumbers when > there can be some more discussion about what would be a reasonable API, > taking into consideration the points brought up in this patch series.
Sounds like a good idea. I'll be at that talk as well. 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/
