> > > > We just can cast phys_addr_t to dma_addr_t here. > > > > > > IME, casting is rarely a proper solution. > > > > *nod* > > > > ptr_phys probably should be a dma_addr_t. Unless this driver is so > > magic that it really wants a physical and not a dma address, in which > > case it needs to use alloc_pages instead of dma_alloc_coherent > > and then call page_to_phys on the returned page, and a very big comment > > explaining why it is so special. > > The scm call takes physical addresses (which happens to be 1:1 with DMA > addresses for this driver). > > This allocation started off (downstream) as a simple kmalloc(), but > while the scm call is being executed an access from Linux will cause a > security violation (that's not handled gracefully). The properties of > dma_alloc is closer, so that's where the code is today. > > Optimally this should be something like alloc_pages() and some mechanism > for unmapping the pages during the call. But no one has come up with a > suitable patch for that. > > > But there's a patch from Stephen for this already (not doing a > typecast). Apparently I missed merging this, so I'll do that. > > https://lore.kernel.org/linux-arm-msm/20190517210923.202131-2-swboyd@xxxxxxxxxxxx/ Bjron, I appreciate for checking this. And also thanks all you guys for the comments here! Thanks,
