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Message-ID: <00f1e968-c140-29b9-dc82-a6f831171d6f@gmail.com> Date: Fri, 26 Aug 2022 11:51:25 +0200 From: Heiner Kallweit <hkallweit1@...il.com> To: Jerome Brunet <jbrunet@...libre.com>, Giuseppe Cavallaro <peppe.cavallaro@...com>, Alexandre Torgue <alexandre.torgue@...s.st.com>, Jose Abreu <joabreu@...opsys.com>, Erico Nunes <nunes.erico@...il.com> Cc: netdev@...r.kernel.org, linux-amlogic@...ts.infradead.org, Kevin Hilman <khilman@...libre.com>, Neil Armstrong <narmstrong@...libre.com>, Vyacheslav <adeep@...ina.in>, Da Xue <da@...sconfused.com>, Qi Duan <qi.duan@...ogic.com> Subject: Re: [RFC/RFT PATCH] net: stmmac: do not poke MAC_CTRL_REG twice on link up On 07.07.2022 12:14, Jerome Brunet wrote: > For some reason, poking MAC_CTRL_REG a second time, even with the same > value, causes problem on a dwmac 3.70a. > > This problem happens on all the Amlogic SoCs, on link up, when the RMII > 10/100 internal interface is used. The problem does not happen on boards > using the external RGMII 10/100/1000 interface. Initially we suspected the > PHY to be the problem but after a lot of testing, the problem seems to be > coming from the MAC controller. > >> meson8b-dwmac c9410000.ethernet: IRQ eth_wake_irq not found >> meson8b-dwmac c9410000.ethernet: IRQ eth_lpi not found >> meson8b-dwmac c9410000.ethernet: PTP uses main clock >> meson8b-dwmac c9410000.ethernet: User ID: 0x11, Synopsys ID: 0x37 >> meson8b-dwmac c9410000.ethernet: DWMAC1000 >> meson8b-dwmac c9410000.ethernet: DMA HW capability register supported >> meson8b-dwmac c9410000.ethernet: RX Checksum Offload Engine supported >> meson8b-dwmac c9410000.ethernet: COE Type 2 >> meson8b-dwmac c9410000.ethernet: TX Checksum insertion supported >> meson8b-dwmac c9410000.ethernet: Wake-Up On Lan supported >> meson8b-dwmac c9410000.ethernet: Normal descriptors >> meson8b-dwmac c9410000.ethernet: Ring mode enabled >> meson8b-dwmac c9410000.ethernet: Enable RX Mitigation via HW Watchdog Timer > > The problem is not systematic. Its occurence is very random from 1/50 to > 1/2. It is fairly easy to detect by setting the kernel to boot over NFS and > possibly setting it to reboot automatically when reaching the prompt. > > When problem happens, the link is reported up by the PHY but no packet are > actually going out. DHCP requests eventually times out and the kernel reset > the interface. It may take several attempts but it will eventually work. > >> meson8b-dwmac ff3f0000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx >> Sending DHCP requests ...... timed out! >> meson8b-dwmac ff3f0000.ethernet eth0: Link is Down >> IP-Config: Retrying forever (NFS root)... >> meson8b-dwmac ff3f0000.ethernet eth0: PHY [0.1:08] driver [Meson G12A Internal PHY] (irq=POLL) >> meson8b-dwmac ff3f0000.ethernet eth0: Register MEM_TYPE_PAGE_POOL RxQ-0 >> meson8b-dwmac ff3f0000.ethernet eth0: No Safety Features support found >> meson8b-dwmac ff3f0000.ethernet eth0: PTP not supported by HW >> meson8b-dwmac ff3f0000.ethernet eth0: configuring for phy/rmii link mode >> meson8b-dwmac ff3f0000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx >> Sending DHCP requests ...... timed out! >> meson8b-dwmac ff3f0000.ethernet eth0: Link is Down >> IP-Config: Retrying forever (NFS root)... >> [...] 5 retries ... >> IP-Config: Retrying forever (NFS root)... >> meson8b-dwmac ff3f0000.ethernet eth0: PHY [0.1:08] driver [Meson G12A Internal PHY] (irq=POLL) >> meson8b-dwmac ff3f0000.ethernet eth0: Register MEM_TYPE_PAGE_POOL RxQ-0 >> meson8b-dwmac ff3f0000.ethernet eth0: No Safety Features support found >> meson8b-dwmac ff3f0000.ethernet eth0: PTP not supported by HW >> meson8b-dwmac ff3f0000.ethernet eth0: configuring for phy/rmii link mode >> meson8b-dwmac ff3f0000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx >> Sending DHCP requests ., OK >> IP-Config: Got DHCP answer from 10.1.1.1, my address is 10.1.3.229 > > Of course the same problem happens when not using NFS and it fairly > difficult for IoT products to detect this situation and recover. > > The call to stmmac_mac_set() should be no-op in our case, the bits it sets > have already been set by an earlier call to stmmac_mac_set(). However > removing this call solves the problem. We have no idea why or what is the > actual problem. > > Even weirder, keeping the call to stmmac_mac_set() but inserting a > udelay(1) between writel() and stmmac_mac_set() solves the problem too. > > Suggested-by: Qi Duan <qi.duan@...ogic.com> > Signed-off-by: Jerome Brunet <jbrunet@...libre.com> > --- > > Hi, > > There is no intention to get this patch merged as it is. > It is sent with the hope to get a better understanding of the issue > and more testing. > > The discussion on this issue initially started on this thread > https://lore.kernel.org/all/CAK4VdL3-BEBzgVXTMejrAmDjOorvoGDBZ14UFrDrKxVEMD2Zjg@mail.gmail.com/ > > The patches previously proposed in this thread have not solved the > problem. > > The line removed in this patch should be a no-op when it comes to the > value of MAC_CTRL_REG. So the change should make not a difference but > it does. Testing result have been very good so far so there must be an > unexpected consequence on the HW. I hope that someone with more > knowledge on this controller will be able to shine some light on this. > > Cheers > Jerome > > drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > index d1a7cf4567bc..3dca3cc61f39 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > @@ -1072,7 +1072,6 @@ static void stmmac_mac_link_up(struct phylink_config *config, > > writel(ctrl, priv->ioaddr + MAC_CTRL_REG); > > - stmmac_mac_set(priv, priv->ioaddr, true); > if (phy && priv->dma_cap.eee) { > priv->eee_active = phy_init_eee(phy, 1) >= 0; > priv->eee_enabled = stmmac_eee_init(priv); Now that we have a3a57bf07de2 ("net: stmmac: work around sporadic tx issue on link-up") in linux-next and scheduled for stable: Jerome, can you confirm that after this commit the following is no longer needed? 2c87c6f9fbdd ("net: phy: meson-gxl: improve link-up behavior") Then I'd revert it, referencing the successor workaround / fix in stmmac.
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