On Fri, Dec 16, 2022 at 01:49:38AM -0800, Christoph Hellwig wrote: > On Fri, Dec 16, 2022 at 12:34:23PM +0300, Serge Semin wrote: > > What about instead of save/restore pattern I'll just change the > > dma_set_mask_and_coherent() method with the dma_set_coherent_mask() > > function call? It seems cleaner. Like this: > > > Thus the platform-specific streaming DMA mask would be preserved. > > Since it's PCIe then having the streaming DMA-mask less than 32-bits > > wide is very much improbable. Moreover DW PCIe AXI-interface can be > > synthesize only with one out of two address bus widths: 32 and 64. > > Where platform-specific means the dwc subdriver? Right. I meant the streaming DMA-mask set by the low-level DWC PCIe drivers (like pcie-qcom(-ep)?.c, pcie-bt1.c, etc). It's very much important to have the real DMA-mask (at least the streaming one) set for the eDMA-capable controllers so the DMA-engine clients would work with the best performance. > Yes, that seems to work. Ok. I'll just use the direct dma_set_coherent_mask() method here then. > Alternatively have a flag that says which streaming mask > to set. I'd prefer to have more flexibility here relying on the low-level drivers to set the mask(s) instead of adding the new flag, just in case if there is vendor-specific IP-core/platform changes in the address bus width. -Serge(y)
