On Sat, Feb 03, 2024 at 12:40:39AM +0300, Serge Semin wrote: > On Fri, Jan 19, 2024 at 06:30:19PM +0530, Mrinmay Sarkar wrote: > > From: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx> > > > > Hyper DMA (HDMA) is already supported by the dw-edma dmaengine driver. > > Unlike it's predecessor Embedded DMA (eDMA), HDMA supports only the > > unrolled mapping format. So the platform drivers need to provide a valid > > base address of the CSRs. Also, there is no standard way to auto detect > > the number of available read/write channels in a platform. So the platform > > drivers has to provide that information as well. > ... > Basically this change defines two versions of the eDMA info > initialization procedure: > 1. use pre-defined CSRs mapping format and amount of channels, > 2. auto-detect CSRs mapping and the amount of channels. > The second version also supports the optional CSRs mapping format > detection procedure by means of the DW_PCIE_CAP_EDMA_UNROLL flag > semantics. Thus should this patch is accepted there will be the > functionality duplication. I suggest to make things a bit more > flexible than that. Instead of creating the two types of the > init-methods selectable based on the mapping format, let's split up > the already available DW eDMA engine detection procedure into the next > three stages: > 1. initialize DW eDMA data, > 2. auto-detect the CSRs mapping format, > 3. auto-detect the amount of channels. > and convert the later two to being optional. They will be skipped in case > if the mapping format or the amount of channels have been pre-defined > by the platform drivers. Thus we can keep the eDMA data init procedure > more linear thus easier to read, drop redundant DW_PCIE_CAP_EDMA_UNROLL flag > and use the new functionality for the Renesas R-Car S4-8's PCIe > controller (for which the auto-detection didn't work), for HDMA with compat > and _native_ CSRs mapping. See the attached patches for details: I am still bound by the opinion of Google's legal team that I cannot accept the code changes that were attached here. I think it's fair to read the review comments (thank you for those), but I suggest not reading the patches that were attached. Bjorn
