From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 08124C43458 for ; Wed, 8 Jul 2026 19:55:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=dtnFbKqySdvbfj21ioTTpBMD7eQEco0l84i2I1V+fvs=; b=vEE2oikg0DLxerZOk15WW/zLdJ i9QbLvEF8mY4zP0BA09fAVz+R/4AwDzH0l9DYZJYj3LtqWzYrpxDcvFz2H+x8rLWMbkcVseuevjR6 AW/hkPhsCdrvuNts/EwE04JMVpiP9Cle/sVnEC1hYFO66yh+L5vEA1YadMltCGTFonkK4Imu2o3F8 VyCJgoMfj7vCgyEvc9msa5VMY4wy3PbTAYUTsvhRNQgzXVj3QNsSKB9hk253vB7wb+zhoHxYbc1c5 xpkIB+kjKrfWxuLbyyGutYPLsQi/8yg6/aOIJ2BF3+1S6ZQq8rxA6r+GmCrzkvmDO1NH2eG8oj1zp jt/nlwOw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1whY5C-00000000H9n-1RPs; Wed, 08 Jul 2026 19:37:22 +0000 Received: from mgamail.intel.com ([198.175.65.17]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1whY5A-00000000H9R-01yV for linux-arm-kernel@lists.infradead.org; Wed, 08 Jul 2026 19:37:21 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1783539440; x=1815075440; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=vy0hljr9IlKplzOF7YFnwyGpNmOwQ9rIA6BOUnYi+94=; b=PvglZMf2Xbj6suquxBavoxiJIklSftDDmzgbdkUe05ApQA9h7OQzGOjb trJxZKFvjbFwwrubmCV8cB9F68mCA17E+z/rbdiTLq7H8CYYaLY4Vrqmh Xr9H7znJssyeVySQmXWe3UTkDGOp1YzjEzQk989xvRdsryviNPbxSpw6j ToTRjs5ZcEPQA5BbLgdrq/4Wrh281RwFW/IKwaUAQRYyj5aV+ICLK35Mi 6CeFC+kFE94hoH2vdYj+5yp0pQ7QyCQ9HiIAQW0j8RTRX9eZcpviPjNFw TdKYJrkyO22jHOTX252h8M1AWXpvDKe8FDmroaJC6pgj6Kob2N2QuUqlr A==; X-CSE-ConnectionGUID: 81q+3OLwQZq6RB73VHgxsA== X-CSE-MsgGUID: 66e+anGERgSBwyjNDMV/Gw== X-IronPort-AV: E=McAfee;i="6800,10657,11841"; a="84234728" X-IronPort-AV: E=Sophos;i="6.25,153,1779174000"; d="scan'208";a="84234728" Received: from orviesa007.jf.intel.com ([10.64.159.147]) by orvoesa109.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jul 2026 12:37:19 -0700 X-CSE-ConnectionGUID: q0VdNDk+S1G66pycizUskg== X-CSE-MsgGUID: sjHt9dcISqKhxWkEm/hGGg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.25,153,1779174000"; d="scan'208";a="254478245" Received: from klitkey1-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.245.100]) by orviesa007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Jul 2026 12:37:16 -0700 Date: Wed, 8 Jul 2026 22:37:14 +0300 From: Andy Shevchenko To: Marcus Folkesson Cc: Wolfram Sang , Michael Hennerich , Bartosz Golaszewski , Andi Shyti , Bartosz Golaszewski , Peter Rosin , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v10 0/7] I2C Mux per channel bus speed Message-ID: References: <20260708-i2c-mux-v10-0-09dca03c8a15@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260708-i2c-mux-v10-0-09dca03c8a15@gmail.com> Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260708_123720_084548_A590A88E X-CRM114-Status: GOOD ( 23.11 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, Jul 08, 2026 at 02:16:12PM +0200, Marcus Folkesson wrote: > This was a RFC on how to implement a feature to have different bus > speeds on different channels with an I2C multiplexer/switch. > As no major complaints on the design came up during the review, I > decided to submit the series without the RFC tag. > > The benefit with this feature is that you may group devices after > the fastest bus speed they can handle. > A real-world example is that you could have e.g. a display running @400kHz > and a smart battery running @100kHz using the same I2C controller. > > There are many corner cases where this may cause a problem for some > hardware topologies. I've tried to describe those I could think of > in the documentation, see Patch #5. > > E.g. one risk is that if the mux driver does not disconnect channels > when Idle, this may cause a higher frequency to "leak" through to > devices that are supposed to run at lower bus speed. > This is not only a "problem" for changing bus speed but could also be > an issue for potential address conflicts. > > This patchset has been used and tested heavily the last months > on a custom board based on a da850 (DaVinci) platform. ... > Changes in v10: > > - Fix gramatics in documentation > - Move {__,}i2c_adapter_set_clk_freq() to i2c-mux.c Can you point to the discussion where it was suggested, please? It was like ages ago (too many patches to review) and I probably missed and/or forgot the rationale for that. Also if we move to i2c-mux, why do we leave it in the adapter namespace? > - Make set_clk_freq() return actual frequency > - Reimplement idle_state (from earlier version) > - Implement example on idle_state for ltc4306 > - Link to v9: https://lore.kernel.org/r/20260324-i2c-mux-v9-0-5292b0608243@gmail.com FWIW, I briefly read the v9 discussion and haven't got the above move, seems wasn't discussed there? -- With Best Regards, Andy Shevchenko