From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=199.89.1.16 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793997246; b=3uFAuJrCKBfJX78tJHc8ovfubwzpXaRl+NYLMKvaX9eFDKvOFKLzBsijDntXigGfj+kT tYAuSrt/HowwwLK1ZHDrAuX3i/Cmf+2w5+9JzSY5qHcNN1eLps9bFJvUKqEqddl6IcHyK ibuFAtDoYGQI1ZJXIVSO1aAP28jxcqqflnS1mm3CadbVvw7YO7hvYtCWcmqpfRpl5u7U1 CxZQYleAf803pwTYCNlE3masFvDJ3vNn/01rVEpB8KQdCayq89cDm8Zhj9xrFDjlVdODY kVOarjUzZnyHR0BzSNUxj76GKMjlJW1+UhPFi3CTx3EOAie1m26zicwr8JVoph95RCQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793997246; h=DMARC-Filter:Received:DKIM-Signature:X-Virus-Scanned:Received: Received:From:To:Cc:Subject:Date:Message-ID:X-Mailer:MIME-Version: Content-Transfer-Encoding; bh=Lf4/8nx82WCQx07flCrOKeUURdG0c0aNEb7IfhxSuaM=; b=SKJRPbL4tYm/oCx+SKC2c8XeTiPYpUhsRdkGVZOZkap4iKjQPrha1Bv/LH1kdtfuJU4T X9WM7/WnCHNPGelNDU/pHUfmfyqMDSijzT6Uu0xmq6Yt0x6YgLXChjHhTNmZr/vRyNvtx qDM6q2thHrtXNtuvVe8dSO5lVeysYEH+xxBXbt9xEqdQ89t7h3wIZV73v8U8g7fIo7ijP ptveI7fUreS7UEOHHvkDGe9uW5jXdKnKHmKXcvUvu9ZrDLWnYooSIr8Qu8GQfDBXbxHxK npN8+rBcaWS8jAg9zr1WDVCqeMHAlKg9QKLkWo9C3vniTFleHtKy6DKMW+EsMOyx/Qg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=acm.org; spf=pass smtp.mailfrom=acm.org; dkim=pass header.d=acm.org header.i=@acm.org header.a=rsa-sha256 header.s=mr01 header.b=kLLmz3LU; arc=none smtp.remote-ip=199.89.1.16 Received: from 013.lax.mailroute.net (013.lax.mailroute.net [199.89.1.16]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9F37C606A326; Fri, 6 Nov 2026 20:34:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 9F37C606A326 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=acm.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=acm.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=acm.org header.i=@acm.org header.a=rsa-sha256 header.s=mr01 header.b=kLLmz3LU Received: from localhost (localhost [127.0.0.1]) by 013.lax.mailroute.net (Postfix) with ESMTP id 4jLrVv3760zlfvps; Fri, 6 Nov 2026 20:33:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=acm.org; h= content-transfer-encoding:mime-version:x-mailer:message-id:date :date:subject:subject:from:from:received:received; s=mr01; t= 1793997237; x=1796589238; bh=Lf4/8nx82WCQx07flCrOKeUURdG0c0aNEb7 IfhxSuaM=; b=kLLmz3LUQjzFeK6nTVh1TmkfH48cTZX6q4j5FiMpDltyQ5p6FWx mn/pRbIx0UqNGSpm7iGwKoPMHEbGNq77locmu15aE5cPALuY6mVn/vqsUcmscEAK O9dVGrDKnHwTpR+1bhrE1j6xOn4heNYZyZmn7w0MzVAXnU6bLrs3cAzyOHS0zSJS KO7PyVj14I09EUsvbQcpk2KR+EcLq0Yv+PSo8mIEuFkDavmWd4IE9nTGcRyNbPXA qhap5jl3e4hFTf+2oJfFKu/siGnykgDply2J5H5E6qEbLszHqThIeeAY3Oze6Ddh wpCf2UQ0UnzTpSnrWOXm8YQPUuxqINuoZ5Q== X-Virus-Scanned: by MailRoute Received: from 013.lax.mailroute.net ([127.0.0.1]) by localhost (013.lax [127.0.0.1]) (mroute_mailscanner, port 10029) with LMTP id ppmzsRS5ENq3; Fri, 6 Nov 2026 20:33:57 +0000 (UTC) Received: from bvanassche.c.googlers.com.com (57.237.82.34.bc.googleusercontent.com [34.82.237.57]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bvanassche@acm.org) by 013.lax.mailroute.net (Postfix) with ESMTPSA id 4jLrVr6hzszlfvpH; Fri, 6 Nov 2026 20:33:56 +0000 (UTC) From: Bart Van Assche To: Peter Rosin Cc: Andi Shyti , Wolfram Sang , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, Bart Van Assche Subject: [PATCH 0/3] i2c: mux: pca954x: Track unknown mux state and report deselect failures Date: Fri, 6 Nov 2026 12:33:19 -0800 Message-ID: X-Mailer: git-send-email 2.56.0.455.g6c5a503b38-goog X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Hi Peter, If a control register write to a pca954x mux fails (e.g. if only the ACK was lost), the write may still have reached the hardware, leaving the mux in an unknown state. Currently the driver records last_chan as 0 (disconnected) after any failed write, which causes idle_state_store() to skip the disconnect write if the idle state is updated to MUX_IDLE_DISCONNECT. In addition, failures in pca954x_deselect_mux() go unnoticed because the i2c-mux core ignores the deselect return value. Track an unknown mux state by setting last_chan to -1 after any failed control register write, split out pca954x_set_idle_state() from pca954x_deselect_mux(), and log a rate-limited warning when deselecting a channel fails. Please consider this series for the next merge window. Thanks, Bart. Bart Van Assche (3): i2c: mux: pca954x: Track unknown channel state i2c: mux: pca954x: Introduce pca954x_set_idle_state() i2c: mux: pca954x: Report deselect failures drivers/i2c/muxes/i2c-mux-pca954x.c | 60 +++++++++++++++++++---------- 1 file changed, 40 insertions(+), 20 deletions(-)