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[2a01:c22:77de:500:880e:dd7c:16c:c9fb]) by smtp.googlemail.com with ESMTPSA id r21-20020a170906a21500b0073c74bee6eesm1248783ejy.201.2022.08.26.13.36.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 26 Aug 2022 13:36:52 -0700 (PDT) Message-ID: <5c8f4cc4-9807-cfe5-7e0a-7961aef5057f@gmail.com> Date: Fri, 26 Aug 2022 22:36:46 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.13.0 Subject: Re: [RFC/RFT PATCH] net: stmmac: do not poke MAC_CTRL_REG twice on link up Content-Language: en-US To: Da Xue Cc: Jerome Brunet , Giuseppe Cavallaro , Alexandre Torgue , Jose Abreu , Erico Nunes , netdev@vger.kernel.org, linux-amlogic@lists.infradead.org, Kevin Hilman , Neil Armstrong , Vyacheslav , Qi Duan References: <20220707101423.90106-1-jbrunet@baylibre.com> <00f1e968-c140-29b9-dc82-a6f831171d6f@gmail.com> From: Heiner Kallweit In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 26.08.2022 17:45, Da Xue wrote: > Hi Heiner, > > I have been running with the patch reverted for about two weeks now > without issue but I have a modified u-boot with ethernet bringup > disabled. > > If u-boot brings up ethernet, all of the GXL boards with more than 1GB > memory experience various bugs. I had to bring the PHY initialization > patch into Linux proper: > https://github.com/libre-computer-project/libretech-linux/commit/1a4004c11877d4239b57b182da1ce69a81c0150c > Thanks for the follow-up. To be acceptable upstream I'm pretty sure that the maintainer is going to request replacing magic number 0x10110181 with or'ing proper constants for the respective bits and fields. > Hope this helps someone. > > Best, > > Da > > On Fri, Aug 26, 2022 at 5:51 AM Heiner Kallweit wrote: >> >> 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 >>> Signed-off-by: Jerome Brunet >>> --- >>> >>> 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.