Hi Jitendra On Fri, Oct 04, 2024 at 09:05:36AM GMT, Jitendra Vegiraju wrote: > Hi Serge, > > On Mon, Sep 16, 2024 at 4:32 PM Jitendra Vegiraju > <jitendra.vegiraju@xxxxxxxxxxxx> wrote: > > > ... > > When you get a chance, I would like to get your input on the approach we need > to take to incrementally add dw25gmac support. > > In the last conversation there were some open questions around the case of > initializing unused VDMA channels and related combination scenarios. > > The hdma mapping provides flexibility for virtualization. However, our > SoC device cannot use all VDMAs with one PCI function. The VDMAs are > partitioned for SRIOV use in the firmware. This SoC defaults to 8 functions > with 4 VDMA channels each. The initial effort is to support one PCI physical > function with 4 VDMA channels. > Also, currently the stmmac driver has inferred one-to-one relation between > netif channels and physical DMAs. It would be a complex change to support > each VDMA as its own netif channel and mapping fewer physical DMAs. > Hence, for initial submission one-to-one mapping is assumed. > > As you mentioned, a static one-to-one mapping of VDMA-TC-PDMA doesn't > require the additional complexity of managing these mappings as proposed > in the current patch series with *struct stmmac_hdma_cfg*. > > To introduce dw25gmac incrementally, I am thinking of two approaches, > 1. Take the current patch series forward using *struct stmmac_hdma_cfg*, > keeping the unused VDMAs in default state. We need to fix the > initialization > loops to only initialize the VDMA and PDMAs being used. > 2. Simplify the initial patch by removing *struct hdma_cfg* from the patch > series and still use static VDMA-TC-PDMA mapping. > Please share your thoughts. > If it helps, I can send patch series with option 2 above after > addressing all other > review comments. IMO approach 2 seems more preferable. Please find my comments to your previous email in this thread: https://lore.kernel.org/netdev/sn5epdl4jdwj4t6mo55w4poz6vkdcuzceezsmpb7447hmaj2ot@gmlxst7gdcix/ > > Appreciate your guidance! Always welcome. Thank you for submitting the patches and your patience to proceed with the review process. -Serge(y) > -Jitendra
