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 DAD5413AA41; Tue, 27 Feb 2024 12:57:55 +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=1709038676; cv=none; b=ByceTqKRSgF0Tqv+JZNLerIt4td7Q4WG3EkIPTVBKRM80j1g4igwl/sak8BzMfEjooMngWTufa+sBIyrsESMyhhlov+tfoeYjnDeNAr2t0vPdMGKOK598m6AnFfpYhey/OdyCBgY6/WpZw5WYH3NV3P7wygjzY/mKySwkvLfwMU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709038676; c=relaxed/simple; bh=tbfKlNGs1QVBMBXcmvRcsmKNsP0qMZgurrAk/JiojBQ=; h=Date:From:To:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=T22TFZWn3t+9lHNY+dXE4Q056MM9hlihov/O/kq2l2v7PNsu8BplrA6dK//5tBuL4FIXae0OXkoCOzsqZ4ZI0Tm9kGrnZ0/rwVNkuskhPMu+2ohCl5AeLbCs0ovOPvCyMwON25sDq9V7Gbe1D7MhfoPqw9SyMl6TwR/bSJTxEUY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UYD8xPb9; 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="UYD8xPb9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 148A0C433C7; Tue, 27 Feb 2024 12:57:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1709038675; bh=tbfKlNGs1QVBMBXcmvRcsmKNsP0qMZgurrAk/JiojBQ=; h=Date:From:To:Subject:References:In-Reply-To:From; b=UYD8xPb9N7w4Vo7PedVTKTFd/tzQpeceNX0F4+/Es7UIV8aEfrjX+WhBdUTFED1L4 ynVxfjFL8QKIkGSKM6nOn2kTlfDWW2cpalI2qckezrxKR98GdZ/0NFH58qctQry3iG 0j1myIQaN9HY+88GBU8tKfPz9NmoGVBSleGFiazQtkjEExAYhXSdzAszzNGf2X+rNH MWCFayiGX4i74iH+3Pbj9B3lzXQqbAaTDyy7mbnvJZ0XWeC+U7tJBAPAI3fU5JFit+ RWKlV0XET8FA3fIDb/5cbjbFQeClRqxiwEFRURhRe0fzx5RhsuOjhWkN6X1Le2bLI1 OYexDxQ2gP0yQ== Date: Tue, 27 Feb 2024 13:57:52 +0100 From: Wolfram Sang To: Andi Shyti , linux-i2c@vger.kernel.org, devicetree-spec@vger.kernel.org, Rob Herring , Krzysztof Kozlowski , Chris Packham Subject: Re: dtschema: i2c: messy situation about timeouts Message-ID: Mail-Followup-To: Wolfram Sang , Andi Shyti , linux-i2c@vger.kernel.org, devicetree-spec@vger.kernel.org, Rob Herring , Krzysztof Kozlowski , Chris Packham References: Precedence: bulk X-Mailing-List: linux-i2c@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="rmZo/KOIoI01PeJJ" Content-Disposition: inline In-Reply-To: --rmZo/KOIoI01PeJJ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > > > - "i2c-scl-clk-low-timeout-us" > > >=20 > > > The description says "Number of microseconds the clock line needs to = be > > > pulled down in order to force a waiting state." What does "forcing a > > > waiting state" mean here? I don't understand this description. > >=20 > > It comes from the specification. The clock stretching is given as > > an interval that can be tweaked depending on the hardware. >=20 > You mean the maximum clock stretching is tweakable? That, in deed, could > be a binding in the future, in theory. Yet, it would need support in the > client drivers. Like a touchscreen driver which assumes a reset after a > certain time of inactivity. To sum it up: a binding defining the maximum time for clock stretching makes sense in theory. I am currently not aware of a controller where this could be used (but I surely don't know them all). Most of them keep SCL low as long as they are busy internally. Not tweakable. So, we defer this until there is a usecase. If we ever add it, the above name of the binding cannot be used anymore because i2c-mpc used it with a different purpose. Not so bad IMO because "scl-clk" is a pleonasm anyway. I'd suggest "i2c-scl-max-stretch-us" but am open for suggestions then. This one can just be deprecated, I'd say. 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