From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Ungerer Subject: Re: [PATCH 0/3]: net: dsa: mt7530: support MT7530 in the MT7621 SoC Date: Mon, 3 Dec 2018 17:20:10 +1000 Message-ID: <0ef5a725-a88a-0a6e-1a69-9106cead6b65@kernel.org> References: <20181130075737.8041-1-gerg@kernel.org> <87r2f2pxpa.fsf@miraculix.mork.no> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: sean.wang@mediatek.com, andrew@lunn.ch, vivien.didelot@savoirfairelinux.com, f.fainelli@gmail.com, netdev@vger.kernel.org, blogic@openwrt.org, neil@brown.name, =?UTF-8?Q?Ren=c3=a9_van_Dorst?= To: =?UTF-8?Q?Bj=c3=b8rn_Mork?= Return-path: Received: from icp-osb-irony-out2.external.iinet.net.au ([203.59.1.155]:51899 "EHLO icp-osb-irony-out2.external.iinet.net.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725850AbeLCHUS (ORCPT ); Mon, 3 Dec 2018 02:20:18 -0500 In-Reply-To: <87r2f2pxpa.fsf@miraculix.mork.no> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: Hi Bjorn, On 30/11/18 10:16 pm, Bjørn Mork wrote: > gerg@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 I applied this to my main debug linux-4.19 kernel. Didn't apply completely cleanly but was easy to fix up. Using that everything came up detected (the 7530 switch) and I could quickly see that it does not suffer the problems I listed below. Both RX and TX packets of any size work! However I also quickly discovered that this driver was pretty unstable. Put a bit of packet load on it, and it would stop responding, CPU lock up, and occasional rcu stalled messages from the kernel. The following change helped alot, but I still get some problems under sustained load and some types of port setups. Still trying to figure out what exactly is going on. --- a/linux/drivers/net/ethernet/mediatek/mtk_eth_soc.c +++ b/linux/drivers/net/ethernet/mediatek/mtk_eth_soc.c @@ -1750,8 +1750,8 @@ static irqreturn_t mtk_handle_irq_rx(int irq, void *_eth) if (likely(napi_schedule_prep(ð->rx_napi))) { __napi_schedule(ð->rx_napi); - mtk_rx_irq_disable(eth, MTK_RX_DONE_INT); } + mtk_rx_irq_disable(eth, MTK_RX_DONE_INT); return IRQ_HANDLED; } @@ -1762,11 +1762,53 @@ static irqreturn_t mtk_handle_irq_tx(int irq, void *_eth) if (likely(napi_schedule_prep(ð->tx_napi))) { __napi_schedule(ð->tx_napi); - mtk_tx_irq_disable(eth, MTK_TX_DONE_INT); } + mtk_tx_irq_disable(eth, MTK_TX_DONE_INT); return IRQ_HANDLED; } Anyway, this really looks like the right approach to me. This driver is clearly capable of supporting the mt7621 ethernet ports. No need for the staging driver. Regards Greg > 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. > >> 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 >