On Wed, Aug 24, 2022 at 09:13:19PM +0300, Serge Semin wrote: > On Wed, Aug 24, 2022 at 11:51:18AM -0500, Bjorn Helgaas wrote: > > On Mon, Aug 22, 2022 at 09:53:32PM +0300, Serge Semin wrote: > > > + val = dw_pcie_readl_dbi(pci, PCIE_DMA_VIEWPORT_BASE + PCIE_DMA_CTRL); > > > + if (val == 0xFFFFFFFF && pci->edma.reg_base) { > > > + pci->edma.mf = EDMA_MF_EDMA_UNROLL; > > > + > > > + val = dw_pcie_readl_dma(pci, PCIE_DMA_CTRL); > > > + } else if (val != 0xFFFFFFFF) { > > > > > Consider PCI_POSSIBLE_ERROR() as an annotation about the meaning of > > 0xFFFFFFFF and something to grep for. > > In this case FFs don't mean an error but a special value, which > indicates that the eDMA is mapped via the unrolled CSRs space. The > similar approach has been implemented for the iATU legacy/unroll setup > auto-detection. So I don't see much reasons to have it grepped, so as > to have a macro-based parametrization since the special value will > unluckily change while having the explicit literal utilized gives a > better understanding of the way the algorithm works. If 0xFFFFFFFF is the result of a successful PCIe Memory Read, and not something synthesized by the host bridge when it handles an Unsupported Request completion, I'm fine with keeping it as is.