From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BDBA127CB02; Fri, 10 Apr 2026 06:42:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775803358; cv=none; b=OhF09kqoiX2fc3V9Zq4zboJg2a8qf/tg0TQGfipbfrDvV7zqocj181uBMEgpY1P93wZwp8TjNrdZe/d7vtWyYzJndBBEqGLkUlxRJ/IDNPdlaNNBVDjfiJEJjCIjfIRpK4770/O7SkJl9R8weGTQzSHjTrGYlgqOiHXNoCMeq+k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775803358; c=relaxed/simple; bh=ExP5iXPCuPkzUAktsanQk4yh+OIzhkbhOeospQVTklo=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=QhbBNZb4utwbUJg6/2M9DLlXMVgJWyRMfXaT/lg+YOLqiOk6uvM5+nhS7giDweI7SsVgHKsCJ4094lO/KqI2xqJX6Ky5gn7POF8oO7oRdUwATZHSyt+JSqWMBlDPONZOkKVGz9V/2OZnvkmEpLmLxOInil3fpe/2MdsWfRKatOI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GpBB+v52; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GpBB+v52" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 60703C2BCAF; Fri, 10 Apr 2026 06:42:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775803358; bh=ExP5iXPCuPkzUAktsanQk4yh+OIzhkbhOeospQVTklo=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=GpBB+v52wHv6pnVOrEy7VUhesQqeQpIwCBiFmFVHF8b1WPyMttGH/gWjGM5bzf99y +onPiDoVmCxXsGH9LWZGzx6M5LUTuq5r3OPu9ZQa1oveMHvDLnaNLGB3/VdrcCgM2m ZmMtonRKKKnODWEZqrKw0Wnxa0C7zgrnRGnuPfYv8MC+hA5gTRtfXcnFcV8rvqMB/D RpG59gn05m/c2Tf6R39RbaAo1s/2+xHKdJAS1yIYiLBs1iBLComo68K80MnIPyN+CP HRcBAnoXd9OnNmamnC3B/Suf6s2zBHa3B2OHR7oroPGarK9+BlPLMw/DAjZXs0NbjD XvMeBOZ39c7EQ== Message-ID: <3c57275e-0574-46e5-9893-053ae5cc22cb@kernel.org> Date: Fri, 10 Apr 2026 08:42:34 +0200 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 1/2] dt-bindings: i2c: ls2x-i2c: Add clock- related properties To: Hongliang Wang Cc: Binbin Zhou , Andi Shyti , Rob Herring , Krzysztof Kozlowski , Conor Dooley , linux-i2c@vger.kernel.org, devicetree@vger.kernel.org, loongarch@lists.linux.dev References: <20260325011852.19079-1-wanghongliang@loongson.cn> <20260325011852.19079-2-wanghongliang@loongson.cn> <20260325-outstanding-weasel-of-fruition-89db37@quoll> <1b5283d8-294c-86de-c3d8-bf205ac24216@loongson.cn> <0d7dfe5b-5e2d-4850-8922-16eb6bd9bcae@kernel.org> <900dc1a4-66ab-411f-8a32-4c6cf339e8ec@kernel.org> <2388acbc-a927-4727-a23c-5ecd7c33a926@kernel.org> <0f560e80-3fbb-c24f-51f9-b4425db17867@loongson.cn> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit On 10/04/2026 05:04, Hongliang Wang wrote: > Hi, Krzysztof > > On 2026/4/9 下午8:11, Krzysztof Kozlowski wrote: >> On 09/04/2026 14:03, Hongliang Wang wrote: >>> I have a question, the input clock of i2c controller can be described by >>> "clocks", >>> but there is no existing attribute can describe the divisor of the input >>> clock, >>> Can I define a new attribute named "clock-div" to describe it in DT >>> bindings? >>> or do you have any standard solutions for the divisor problem? Thank you. >>> >> You should determine/calculate the divisor in the driver code, depending >> on clocks and bus frequencies. You don't need a property for that, usually. > > Not only clocks and bus frequencies, but also a third property is required. > > The frequency divison calculation formula of i2c is > Prcescale = clock_a/(clock_div*clock_s)-1 > > There is three parameters in this formula: > clock_a represents the input clock, which is described by "clocks", > clock_s represents the i2c bus frequency, which is described by > "clock-frequency", > but there is no existing property to describe clock_div, which has > different value > on different platform (for example, it is 5 on 7a1000/7a2000, 4 on > 2K1000/2K2000, > 5.5 on 2K3000.), So I need a property to describe clock_div in this formula. So it is fixed per compatible? Then you do not need. Best regards, Krzysztof