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[46.193.119.166]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43b919e7111sm6381199f8f.37.2026.03.26.02.10.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 26 Mar 2026 02:10:48 -0700 (PDT) From: Fidelio Lawson X-Google-Original-From: Fidelio Lawson Subject: [PATCH 0/3] ksz87xx: add support for low-loss cable equalizer errata Date: Thu, 26 Mar 2026 10:10:20 +0100 Message-Id: <20260326-ksz87xx_errata_low_loss_connections-v1-0-79a698f43626@exotec.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAPz3xGkC/yWNwQrCMBBEf6Xs2UBMair+ikhI4qpRSWS32mDpv 7vqYQ4PZt7MwEgZGXbdDISvzLkWgfWqg3QJ5YwqH4XBaOO0NVbd+L0dWvNIFMbg73WSMPtUS8E 0ypxVdBscHJrYawtiehCecvu97A9/5me8Sv2rhmX5AGYdrFmHAAAA X-Change-ID: 20260323-ksz87xx_errata_low_loss_connections-b65e76e2b403 To: Woojung Huh , UNGLinuxDriver@microchip.com, Andrew Lunn , Vladimir Oltean , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Marek Vasut , Maxime Chevallier Cc: Woojung Huh , netdev@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Fidelio Lawson X-Mailer: b4 0.15.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1774516248; l=1968; i=fidelio.lawson@exotec.com; s=20260326; h=from:subject:message-id; bh=jlfzUqL5XaI195zD9OLF2Th7Si2B8ruPet0hTv9v4Ns=; b=S/roDsVN3Wq7zvzTF/aHCH1/5dfMWW/cty9n3DjadfYyFJRUSGTSmsQ7sEQzyfLTGePzH4qFA C9n3mmOj4v1CP05vTUtTDjYs5aj3KsTim7BTPyQuXA3t5uKvt8HucI8 X-Developer-Key: i=fidelio.lawson@exotec.com; a=ed25519; pk=866eH9Bmmpjc+ctgkr5T1uXxBefZzob3tEEuiVWZ6BI= Hello, This patch series adds support for the "Module 3: Equalizer fix for short cables" erratum documented in Microchip KSZ87xx Errata DS80000687C. According to the erratum, the embedded PHY receiver in KSZ87xx switches is tuned by default for long, high-loss Ethernet cables. When operating with short or low-loss cables (for example CAT5e or CAT6), the PHY equalizer may over-amplify the incoming signal, leading to internal distortion and link establishment failures. Microchip provides two workarounds, each requiring a write to a different indirect PHY register access mechanism. This series introduces: - Device Tree bindings to enable the errata fix and select workaround 1 or 2, - driver-level parsing of these bindings, - implementation of the indirect register programming sequence required for Workaround 1 and Workaround 2. If the errata is enabled but no mode is explicitly selected, the driver defaults to Workaround 1, following Microchip guidance. The feature is opt-in and does not affect existing platforms that do not enable the errata. Tested on KSZ8795 with both Workaround 1 and Workaround 2. Signed-off-by: Fidelio Lawson --- Fidelio Lawson (3): dt-bindings: dsa: microchip: add KSZ low-loss cable errata properties net: dsa: microchip: parse KSZ87xx low-loss errata from DT net: dsa: microchip: implement KSZ87xx Module 3 low-loss cable errata .../devicetree/bindings/net/dsa/microchip,ksz.yaml | 18 ++++++ drivers/net/dsa/microchip/ksz8.c | 71 ++++++++++++++++++++++ drivers/net/dsa/microchip/ksz8.h | 1 + drivers/net/dsa/microchip/ksz_common.h | 9 +++ 4 files changed, 99 insertions(+) --- base-commit: 2d1373e4246da3b58e1df058374ed6b101804e07 change-id: 20260323-ksz87xx_errata_low_loss_connections-b65e76e2b403 Best regards, -- Fidelio Lawson