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[94.255.221.162]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6b38a1dacb6sm4299381a12.28.2026.10.19.10.37.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Oct 2026 10:37:11 -0700 (PDT) From: Yongzhao Chen To: netdev-bot+sashiko@kernel.org Cc: netdev@vger.kernel.org, Christian Marangi , Andrew Lunn , Vladimir Oltean , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Russell King , Florian Fainelli , linux-kernel@vger.kernel.org, Ziyang Huang Subject: Re: [PATCH net v5] net: dsa: qca8k: preserve port state across MTU changes Date: Mon, 19 Oct 2026 19:37:06 +0200 Message-ID: <20261019173706.198461-1-yongzhao.derek@gmail.com> X-Mailer: git-send-email 2.55.0.windows.5 In-Reply-To: <179240775070.3135.2434822808609533404@kernel.org> References: <20261015104550.43169-1-yongzhao.derek@gmail.com> <179240775070.3135.2434822808609533404@kernel.org> X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Mon, 19 Oct 2026 11:02:30 +0000 netdev-bot+sashiko@kernel.org wrote: > That path only reverts the conduit MTU. Does the switch-global > MAX_FRAME_SIZE register then keep the new value, while DSA and the > conduit keep the old MTU? Nothing seems to write the old frame size > back. Yes. With v5, a failed restore after a successful frame-size write leaves the new frame size in the switch while DSA keeps the old MTU. On a fixed-link CPU port the same failure can keep the MAC off until a link flap or reboot. > Two options: keep returning success once MAX_FRAME_SIZE has been > written, or roll MAX_FRAME_SIZE back on failure. Either way, should a > failed restore stop being treated as the saved state on later calls? v6 takes the first option: it returns the result of the frame-size write, and a later restore failure no longer replaces it. A failed PORT_STATUS write now keeps its target and is retried every second from delayed work, so a fixed-link port does not depend on another mac_link_up(). Newer port decisions replace the pending bits. The next MTU change first recovers pending writes on ports 0 and 6 and returns an error if that fails, so a failed restore is not taken as the saved state. A userspace harness that compiles the driver functions and dsa_user_change_mtu() now covers both cases, and v5 fails it. v6 has not been tested on hardware. I will send it separately. Thanks, Yongzhao Chen pw-bot: cr