From: ok...@codeaurora.org Date: Mon, 18 Apr 2016 01:06:27 -0400 > On 2016-04-18 00:00, David Miller wrote: >> From: Sinan Kaya <ok...@codeaurora.org> >> Date: Sat, 16 Apr 2016 18:23:32 -0400 >> >>> Current code is assuming that the address returned by >>> dma_alloc_coherent >>> is a logical address. This is not true on ARM/ARM64 systems. This >>> patch >>> replaces dma_alloc_coherent with dma_map_page API. The address >>> returned >>> can later by virtually mapped from the CPU side with vmap API. >>> Signed-off-by: Sinan Kaya <ok...@codeaurora.org> >> You can't do this. >> The DMA map page API gives non-coherent mappings, and thus requires >> proper flushing. >> So a straight conversion like this is never legitimate. > > I would agree on proper dma api usage. However, the code is already > assuming coherent architecture by mapping the cpu pages as > page_kernel. > > Dma_map_page returns cached buffers and you don't need cache flushes > on coherent architecture to make the data visible.
All you are telling me is that there are two bugs instead of one, so now both need to be fixed.
