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[90.63.244.31]) by smtp.gmail.com with ESMTPSA id t9-20020a05600c198900b0037c0342cb62sm7842262wmq.4.2022.03.02.06.44.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 02 Mar 2022 06:44:14 -0800 (PST) References: <1jczjzt05k.fsf@starbuckisacylon.baylibre.com> <6b04d864-7642-3f0a-aac0-a3db84e541af@gmail.com> <1e828df4-7c5d-01af-cc49-3ef9de2cf6de@gmail.com> User-agent: mu4e 1.6.10; emacs 27.1 From: Jerome Brunet To: Heiner Kallweit , Erico Nunes , Martin Blumenstingl Cc: Alexandre Torgue , Giuseppe Cavallaro , Jose Abreu , Kevin Hilman , Neil Armstrong , linux-amlogic@lists.infradead.org, netdev@vger.kernel.org, "open list:ARM/Rockchip SoC..." , linux-sunxi@lists.linux.dev Subject: Re: net: stmmac: dwmac-meson8b: interface sometimes does not come up at boot Date: Wed, 02 Mar 2022 14:39:47 +0100 In-reply-to: <1e828df4-7c5d-01af-cc49-3ef9de2cf6de@gmail.com> Message-ID: <1j8rts76te.fsf@starbuckisacylon.baylibre.com> Precedence: bulk X-Mailing-List: linux-sunxi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Wed 02 Mar 2022 at 12:01, Heiner Kallweit wrote: > On 02.03.2022 11:33, Erico Nunes wrote: >> On Sat, Feb 26, 2022 at 2:53 PM Heiner Kallweit wrote: >>> Just to rule out that the PHY may be involved: >>> - Does the issue occur with internal and/or external PHY? >> >> My target boards have the internal phy only. It is not possible for me >> at the moment to test it with an external phy. >> >>> - Issue still occurs in PHY polling mode? (disable PHY interrupt in dts) >> >> Thanks for suggesting this. I did tests with this and it seems to be a >> workaround. >> With phy interrupt on recent kernels (around v5.17-rc3) I'm able to >> reproduce the issue relatively easily over a batch of a hundred jobs. >> With my tests with the phy in polling mode, I have not been able to >> reproduce so far, even with several hundred jobs. >> > It's my understanding that in the problem case the "aneg complete" > interrupt fires, but no data flows. > This might indicate a timing issue. According to the meson PHY driver > (I don't have the datasheet) the PHY doesn't have a "link up" interrupt > source, just the mentioned "aneg complete". > > Below I send an experimental patch that delays the link up processing > a little and eliminates not needed interrupt sources. > Could you please test it with PHY interrupts enabled? > > > By the way, to all: > I found that interrupt mode is broken in fixed (aneg disabled) mode, > because link-up isn't signaled. Experiments showed that irq source > bit 7 can be used to fix this, but this bit isn't documented in the > driver. > >> For completeness I also tested 46f69ded988d (from my initial analysis) >> and setting the phy to polling mode there does not make a difference, >> issue still reproduces. So it may have been a different bug. Though I >> guess at this point we can disregard that and focus on the current >> kernel. >> >> I tried adding a few debugs and delays to the interrupt code path in >> drivers/net/phy/meson-gxl.c but nothing gave me useful info so far. >> >> Do you have more advice on how to proceed from here? >> >> Thanks >> >> Erico > > Heiner Hi, I also did some tests on my side as well. Mostly with v5.10.93 ATM It is true that I can recall seeing this issue only on boards using the internal PHY (g12 and gxl board for me - I don't have meson8b boards) I tried on the u200 (g12 based). Being the ref design it has both the internal and external interfaces and I can choose. To my surprise, I could not reproduce the issue on it with the internal PHY ... until I noticed that eMMC was initialising more or less at the same time as the network. I disabled the eMMC, out of curiosity, and the issue was back. Like Heiner, I suspect a timing issue - at this stage, I can't tell if it is PHY related though. I also tried with the external phy, could not reproduce. Unfortunately, as we can see from the first test on the u200, not reproducing is not really a proof and it difficult to conclude. Like Erico, I tried bisecting but I ended up on a BT merge ... Clearly inconclusive :( Disabling the IRQ is an interesting test but, on my side, I have mixed results (on the libretech-cc this time): * I first tried quickly while bisecting, on commit 5.6.0-rc3-01434-g8d4ccd7770e7: - With IRQ => NOK - POLL => NOK Seeing Erico's report, I thought maybe I mixed things up so I tried again, doubled checked IRQ were disabled ... still broken. There was another commit I reproduce it without IRQ but I lost it. * I also tried on v5.10.93: - With IRQ => NOK - POLL => OK ... (well, I got bored before the issue showed up) It seems that switching to polling, in some case, changes the timings just enough to hide the issue ... but not always. Unless I forgot to consider something else ?? Ideas ? If I understand the proposed patch correctly, it is mostly about the phy IRQ. Since I reproduce without the IRQ, I suppose it is not the problem we where looking for (might still be a problem worth fixing - the phy is not "rock-solid" when it comes to aneg - I already tried stabilising it a few years ago) TBH, It bothers me that I reproduced w/o the IRQ. The idea makes sense :/ > > > diff --git a/drivers/net/phy/meson-gxl.c b/drivers/net/phy/meson-gxl.c > index 7e7904fee..0acb3a99a 100644 > --- a/drivers/net/phy/meson-gxl.c > +++ b/drivers/net/phy/meson-gxl.c > @@ -7,6 +7,7 @@ > * Author: Neil Armstrong > */ > #include > +#include > #include > #include > #include > @@ -209,12 +210,7 @@ static int meson_gxl_config_intr(struct phy_device *phydev) > if (ret) > return ret; > > - val = INTSRC_ANEG_PR > - | INTSRC_PARALLEL_FAULT > - | INTSRC_ANEG_LP_ACK > - | INTSRC_LINK_DOWN > - | INTSRC_REMOTE_FAULT > - | INTSRC_ANEG_COMPLETE; > + val = INTSRC_LINK_DOWN | INTSRC_ANEG_COMPLETE; > ret = phy_write(phydev, INTSRC_MASK, val); > } else { > val = 0; > @@ -240,6 +236,9 @@ static irqreturn_t meson_gxl_handle_interrupt(struct phy_device *phydev) > if (irq_status == 0) > return IRQ_NONE; > > + if (irq_status & INTSRC_ANEG_COMPLETE) > + msleep(100); > + > phy_trigger_machine(phydev); > > return IRQ_HANDLED;