On Fri, Jan 26, 2018 at 2:53 AM, Christoph Hellwig <hch@xxxxxx> wrote: > On Wed, Jan 24, 2018 at 12:04:58PM -0800, Florian Fainelli wrote: >> This looks nicer than the current shape, but this still requires to >> register a PCI fixup to override phys_to_dma() and dma_to_phys(), and it >> would appear that you have dodged my question about how this is supposed >> to fit with an entirely modular PCIe root complex driver? Are you >> suggesting that we split the module into a built-in part and a modular part? > > I don't think entirely modular PCI root bridges should be a focal point > for the design. If we happen to support them by other design choices: > fine, but they should not be a priority. I disagree. If there is one common thing our customers request it is the ability to remove (or control the insmod of after boot) the pcie RC driver. I didn't add this in as a "nice-to-have". > > That being said if we have core dma mapping or PCIe code that has > a list of offsets and the root complex only populates them it should > work just fine. I'm looking at arch/arm/include/asm/dma-mapping.h. In addition to overriding dma_to_phsy() and phys_to_dma(), it looks like I may have to define __arch_pfn_to_dma(), __arch_dma_to_pfn(), __arch_dma_to_virt(), __arch_virt_to_dma(). Do you agree or is this not necessary? If it is, this seems more intrusive than our pcie-brcmstb-dma.c solution which doesn't require tentacles into major include files and Kconfigs. Another issue is that our function wrappers -- depending upon whether we are dealing with a pci device or not -- will have to possibly call the actual ARM and ARM64 definitions of these functions, which have been of course #ifdef'd out. This means that our code must contain identical copies of these functions' code and that the code must somehow be kept in sync. Do you see a solution to this? Jim
