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Received: from shell.armlinux.org.uk ([fd8f:7570:feb6:1:5054:ff:fe00:4ec]:42350) by pandora.armlinux.org.uk with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jxtP3-0004QT-Pn; Tue, 21 Jul 2020 15:37:57 +0100 Received: from linux by shell.armlinux.org.uk with local (Exim 4.92) (envelope-from ) id 1jxtP2-000641-Re; Tue, 21 Jul 2020 15:37:56 +0100 Date: Tue, 21 Jul 2020 15:37:56 +0100 From: Russell King - ARM Linux admin To: Andrew Lunn , Gregory Clement , Jason Cooper , Kishon Vijay Abraham I , Rob Herring , Sebastian Hesselbarth , Vinod Koul Subject: [PATCH v2 0/3] Fix Armada 38x mvneta lockups when switching speeds Message-ID: <20200721143756.GT1605@shell.armlinux.org.uk> MIME-Version: 1.0 Content-Disposition: inline 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-20200721_103804_911112_D81E5B19 X-CRM114-Status: GOOD ( 14.02 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.4 on merlin.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record 0.0 SPF_NONE SPF: sender does not publish an SPF Record -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain 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: devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Hi, While testing phylink over the weekend, I found it was possible to cause the mvneta hardware to lockup in various weird and wonderful ways by switching the interface speed between 1G and 2.5G repeatedly. It didn't require a rapid switching, but one switch every few seconds. Symptoms included one or more of: - Timeout while trying to stop transmit (seen once) - 2500BASE-X link negotiation failure (fails to exchange link word.) - Detects lack of sync, but fails to flag 10ms of sync failure. - SyncOk bit randomly toggles. Once the hardware gets into a "bad" state, trying to recover it by using the mvneta GMAC port reset fails to resolve the issue. Disabling the port also fails to recover it. The only way to recover seemed to be via a reboot. Many solutions to solve this were tried in various combinations - while changing the COMPHY configuration: - putting the GMAC into reset - disabling the GMAC port - augmenting the COMPHY configuration to try to "cleanly" disable the COMPHY via phy_power_down() and reconfigure it via phy_power_up(), including resetting parts of the COMPHY and re-running the RX initialisation. None of that worked. It was then discovered from the u-boot sources that there is an undocumented register that has a lane-specific bit set at the end of COMPHY initialisation, once the loosely documented COMPHY setup has completed. Experimentation with that showed that if the lane specific bit is cleared before changing the COMPHY "GEN" configuration, and set afterwards, mvneta no longer locks up. Unfortunately, this undocumented register is not part of the COMPHY register set that we map - it is located in a region of "System Registers" which are shared between multiple different devices. Who should be responsible for mapping this register (mvneta or COMPHY) was considered; the register is only present on Armada 38x systems, and seemingly not on Armada 37x or Armada 37xx systems. It seems that it is a system-level register. The COMPHYs seem to be system specific, so let's make it part of the COMPHY. With no real information on this register, all we can do is guess about it's function and how to fit it into the system. .../bindings/phy/phy-armada38x-comphy.txt | 10 ++++- arch/arm/boot/dts/armada-38x.dtsi | 3 +- drivers/phy/marvell/phy-armada38x-comphy.c | 45 ++++++++++++++++++---- 3 files changed, 49 insertions(+), 9 deletions(-)