On Fri, Nov 30 2018, Bjørn Mork wrote: > g...@kernel.org writes: > >> I have been working towards supporting the MT7530 switch as used in the >> MediaTek MT7621 SoC. Unlike the MediaTek MT7623 the MT7621 is built around >> a dual core MIPS CPU architecture. But underneath it is what appears to >> be the same 7530 switch. > > Great! Good to see someone pushing this idea forward. > >> The following 3 patches are more of an RFC than anything. They allow >> use of the mt7530 dsa driver on this device - though with some issues >> still to resolve. The primary change required is to not use the 7623 >> specific clock and regulator setup - none of that applies when using >> the 7621 (and maybe other devices?). The other change required is to >> set the 7530 MFC register CPU port number and enable bit. >> >> The unresolved issues I still have appear to be more related to the >> MT7621 ethernet driver (drivers/staging/mt7621-eth/*). I am hoping >> someone might have some ideas on these. I don't really have any good >> documentation on the ethernet devices on the 7621, so I am kind of >> working in the dark here. > > No offense, but the mt7621-eth driver in staging is horrible. What both > René and I have had some success with is adapting the mtk_eth_soc driver > already in drivers/net/ethernet/mediatek/. Yes, I know this is supposed > to be for other SoCs, but the basic design is obviously the same. > > I have had some success with a first hackish attemt based on OpenWrt. > You can find the early tree here, but note that my focus was basically > getting one specific MT7621 board up and running: > https://github.com/bmork/LEDE/tree/mt7621-with-mainline-eth-driver > > This patch has most of the necessary changes to enable that driver for > MT7621: > https://github.com/bmork/LEDE/commit/3293bc63f5461ca1eb0bbc4ed90145335e7e3404 > > Not a big deal, as you can see. There is of course a reason I didn't > submit this here yet: It is by no means finished... But it works. And I > have both GMACs working with this driver, which was my primary goal.
Thanks a lot for posting this. I'd be very happy to see the staging driver disappear once this is ready and in mainline. I got your patch working on 4.20-rc5 and did a performance comparison. With the staging driver (using iperf3) I get 220 MBit/sec in 680 MBit/sec out with the patched mainline driver I get 190 MBit/sec in 93 MBit/sec out (numbers are a bit rubbery, but within 10%) I haven't looked into why this might be, but thought I would mention it. Strangely when I test with scp, I get about 10MB/sec in both directions with both drivers. Maybe the CPU limits encryption speed. I have a 4.4-based kernel where I get 940MBit/sec both ways - using a precursor of the current staging driver. Thanks, NeilBrown > >> 1. TX packets are not getting an IP header checksum via the normal >> off-loaded checksumming when in DSA mode. I have to switch off >> NETIF_F_IP_CSUM, so the software stack generates the checksum. >> That checksum offloading works ok when not using the 7530 DSA driver. > > Hmm. How do I test this? > >> 2. Maximal sized RX packets get silently dropped. So receive side packets >> that are large (perfect case is the all-but-last packets in a fragemented >> larger packet) appear to be dropped at the mt7621 ethernet MAC level. >> The 7530 MIB switch register counters show receive packets at the physical >> switch port side and at the CPU switch port - but I get no packets >> received or errors in the 7621 ethernet MAC. If I set the mtu of the >> server at the other end a little smaller (a few bytes is enough) then >> I get all the packets through. It seems like the DSA/VLAN tag bytes >> are causing a too large packet to get silently dropped somewhere. > > Are you referring to the configured MTU size or some other maximal size? > If MTU, then I don't seem to have this issue with the driver from > drivers/net/ethernet/mediatek/. > > > > Bjørn
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