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Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:37766) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jtuo6-0001px-Qr; Fri, 10 Jul 2020 16:19:22 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1jtuo5-0003Ll-OY; Fri, 10 Jul 2020 16:19:21 +0100 Date: Fri, 10 Jul 2020 16:19:21 +0100 From: Russell King - ARM Linux admin To: Vinod Koul Subject: Re: [PATCH 2/2] phy: armada-38x: fix NETA lockup when repeatedly switching speeds Message-ID: <20200710151921.GJ1551@shell.armlinux.org.uk> References: <20200630160452.GD1551@shell.armlinux.org.uk> <20200701065727.GY2599@vkoul-mobl> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200701065727.GY2599@vkoul-mobl> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200710_111932_005355_0B6CF184 X-CRM114-Status: GOOD ( 25.85 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Andrew Lunn , Jason Cooper , devicetree@vger.kernel.org, Gregory Clement , Kishon Vijay Abraham I , Rob Herring , linux-arm-kernel@lists.infradead.org, Sebastian Hesselbarth Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Jul 01, 2020 at 12:27:27PM +0530, Vinod Koul wrote: > On 30-06-20, 17:05, Russell King wrote: > > The mvneta hardware appears to lock up in various random ways when > > repeatedly switching speeds between 1G and 2.5G, which involves > > reprogramming the COMPHY. It is not entirely clear why this happens, > > but best guess is that reprogramming the COMPHY glitches mvneta clocks > > causing the hardware to fail. It seems that rebooting resolves the > > failure, but not down/up cycling the interface alone. > > > > Various other approaches have been tried, such as trying to cleanly > > power down the COMPHY and then take it back through the power up > > initialisation, but this does not seem to help. > > > > It was finally noticed that u-boot's last step when configuring a > > COMPHY for "SGMII" mode was to poke at a register described as > > "GBE_CONFIGURATION_REG", which is undocumented in any external > > documentation. All that we have is the fact that u-boot sets a bit > > corresponding to the "SGMII" lane at the end of COMPHY initialisation. > > > > Experimentation shows that if we clear this bit prior to changing the > > speed, and then set it afterwards, mvneta does not suffer this problem > > on the SolidRun Clearfog when switching speeds between 1G and 2.5G. > > > > This problem was found while script-testing phylink. > > > > Signed-off-by: Russell King > > --- > > arch/arm/boot/dts/armada-38x.dtsi | 3 +- > > lgtm, i need ack for dts parts before I can apply this I'm not sure what the situation is for Bootlin, but they don't seem to be very responsive right now (covid related?) What I know from what I've been party to on netdev is that Bootlin sent a patch for the MVPP2 driver, and the very next day someone reported that the patch caused a bug. Unfortunately, the patch got picked up anyway, but there was no response from Bootlin. After a month or so, -final was released containing this patch, so now it had become a regression - and still no response from Bootlin. Eventually the bug got fixed - not because Bootlin fixed it, but because I ended up spending the time researching how that part of the network driver worked, diagnosing what was going on, and eventually fixing it in the most obvious way - but it's not clear that the fix was the right approach. Bootlin never commented. See 3138a07ce219 ("net: mvpp2: fix RX hashing for non-10G ports"). So, I think we have to assume that Bootlin are struggling right now, and as it's been over a week, it's unlikely that they are going to respond soon. What do you think we should do? I also note that Rob has not responded to the DT binding change either, despite me gently prodding, and Rob processing a whole raft of DT binding stuff yesterday. I can split the DTS change from the rest of the patch, but I don't think that really helps without at least the binding change being agreed. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last! _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel