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 X-Spam-Level: X-Spam-Status: No, score=-7.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1BCE3C43331 for ; Wed, 1 Apr 2020 14:42:10 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id B0E7520719 for ; Wed, 1 Apr 2020 14:42:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="UKtCs99r" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B0E7520719 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=the-dreams.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type:Cc: List-Subscribe:List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id: In-Reply-To:MIME-Version:References:Message-ID:Subject: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=IqlO8X5fgBEH8DJIzXcaq3n4JtjVTxq8zQfJniakFHA=; b=UKtCs99rJ+9aqo2oaAgLJkqWQ ap93OB/VjOnczNdwm+k43/+isGBgVbiAUowVgcNdVm+LgZrySnj4g3uQiWfgFj0W5yMXFd6zwUxPc CcM4VJU1a4aKBs8NrQlv5+K81bWWxxFPJUsGmhD0TP/9OZTG5H/Sc2uP2cMaMAEz+MduuL8L0r5/L 2oDU3jDTJQ8kkXBHwzojjleGE+sWgVGoy1cUTnK44GWtEZS0I37xM/EGgK12W2KLUStWV/AMODGKc f0uKxdyfbMIDMXFDGB07lruiUtDf5Bf2AKR7BMibcoR1mTd2ARR55bhFUU7SAN922wlUWP7Im/evl SmpFS1M/A==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jJeZE-0002tk-Dt; Wed, 01 Apr 2020 14:42:08 +0000 Received: from sauhun.de ([88.99.104.3] helo=pokefinder.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jJeZA-0002id-9j for linux-arm-kernel@lists.infradead.org; Wed, 01 Apr 2020 14:42:06 +0000 Received: from localhost (p54B33220.dip0.t-ipconnect.de [84.179.50.32]) by pokefinder.org (Postfix) with ESMTPSA id F04C62C1EEC; Wed, 1 Apr 2020 16:41:59 +0200 (CEST) Date: Wed, 1 Apr 2020 16:41:59 +0200 From: Wolfram Sang To: Laine Jaakko EXT Subject: Re: [PATCH] i2c: xiic: Support disabling multi-master in DT Message-ID: <20200401143254.GA2409@ninjato> References: <20200218135627.24739-1-ext-jaakko.laine@vaisala.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200401_074204_525296_F5292C5F X-CRM114-Status: GOOD ( 12.15 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "michal.simek@xilinx.com" , Shubhrajyoti Datta , "linux-arm-kernel@lists.infradead.org" , "linux-i2c@vger.kernel.org" Content-Type: multipart/mixed; boundary="===============3173777359941407615==" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org --===============3173777359941407615== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="tsOsTdHNUZQcU9Ye" Content-Disposition: inline --tsOsTdHNUZQcU9Ye Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > The multi-master -binding is documented here as boolean and encodes a > Boolean by either existing or not existing in device tree. It is also > used in other drivers so I couldn't do much about it missing meaning > False. > https://github.com/torvalds/linux/blob/master/Documentation/devicetree/bi= ndings/i2c/i2c.txt > I originally had a custom device tree entry where the default was for > multi-master to be enabled before I noticed the pre-existing binding. >=20 > Maybe if the multi-master binding was changed from Boolean to for > example a string property (multi-master =3D "ON" / multi-master =3D > "OFF"), code could still just check the existence with > "of_property_read_bool()" first, where property missing means "OFF" > and property existing means "ON"(like before) if there is no text > associated. Xiic driver would then only disable multimaster, if device > tree explicitly contains multi-master =3D "OFF". >=20 > This should be able to maintain driver backwards compatibility with > old device trees, but requires binding documentation change and all > drivers should likely be updated to also accept the new style of > multi-master property to be consistent. This is also not as clean as > the old Boolean property in my opinion. I agree. I don't want to change the old "multi-master" binding like above because that would be quite intrusive for other drivers and confusing when trying to understand the binding. My best bet is to introduce another binding "single-master" which says clearly that we are the only bus master on that bus. Both bindings missing means then "unclear". I think this matches reality best. Opinions? --tsOsTdHNUZQcU9Ye Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEOZGx6rniZ1Gk92RdFA3kzBSgKbYFAl6EqDcACgkQFA3kzBSg KbbF6g//ca5Zr0fqlMxxbB0GPUdCqBey97V9YduvQi9tCkt5ufyg12ypS3iSTUFq v/0+sDd2J7zidl4TXfwlMrn7fiWOHENsJLX++78dSK1o+d1nx4MXpgBDhQaOu3+q MjAspDeQPquTY4wPbMQCprVkDhTpSANRUvTwD5FdTmOJt+YA8luySNaWL/nQmWKj 8UqAQyn1vgmNWaAv1ch1jr8+vuE+YV+i4opSd3wEQcXXEy3v0hYNSONyFf1WlRul T1ITLRaVBgY9uJNhIbqfi/khS3VV/Mtp/GIaGHgl+vkGtf0Uv3cLvednYmNUP/lx y0PcaIXobivy6iKHNpIUJ0J8Xi2aL5d0VSABBrHuqi3GoOQM6hfkbOqhxHb4QgYS RMfhUAYztM/AdHcss5xb/oC3hPCZgzqPQg1rxDI+IGOOQoJfx+3vpM/fpp4oqCKJ fwSxC0rF2OQsWXCc9rIRyuvVrKaXfAE43uysyATYC6zMPTH+fmd8trREk2W7nitF xxD+7UypFDmSZlhZf1v9csUIeWve/gjjvhvtnYlTJHc1bC62dpc/6UR+6NEtEM+0 F5Tttow5S+jwY36zJwIkFrhmqsgpPPrUWEYPSXAdgb30B5VMRaMcwMGkYUaVOGBn ue2kmuU3euXXpBMjbAObF6bRfuwq7ce0Hqg47NGJQj0lvlJc1AY= =LbAj -----END PGP SIGNATURE----- --tsOsTdHNUZQcU9Ye-- --===============3173777359941407615== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel --===============3173777359941407615==--