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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 C9D71C433E0 for ; Tue, 21 Jul 2020 06:22:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A06A4208E4 for ; Tue, 21 Jul 2020 06:22:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595312544; bh=47dJEVMdxrfXF2oYeyAzojzZPGNAbJ4RDRe72YadUlk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=SHJ8qhCsnbtSmqVkqeOanLOM3KUnWg9LlJ6YG9hpaxYns9MBc7pcSRitBuaVDENpw lXb6IMfFvNZ1gv7hu786bt6LQheyrCzutnMwpbiBGoQW899qIc0/FpCtI3AKPkhmVj lKXU4dEWV0Zog1u597e9WNtbAyL19r8N7ZRFZEcs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726108AbgGUGWY (ORCPT ); Tue, 21 Jul 2020 02:22:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:37318 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726053AbgGUGWX (ORCPT ); Tue, 21 Jul 2020 02:22:23 -0400 Received: from localhost (p5486cdb1.dip0.t-ipconnect.de [84.134.205.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 9CB0E20792; Tue, 21 Jul 2020 06:22:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1595312543; bh=47dJEVMdxrfXF2oYeyAzojzZPGNAbJ4RDRe72YadUlk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=aFO1sfzyiSsQ1aRHew1Fs3t3HI9JCj0gnJYlQfk/Wn+lFIwh2wcj9fdH+Uf4agaTQ oHaCrMb0N0PX0kMcmZoQu3HE3aEJxxd8pAinpjgDk+f0OYHP+pE+UPzSlTZQ+7FEWP CWY0zTjGWsjW1KPmZOKcxbu5Z+ZJNG/oCu+weqRQ= Date: Tue, 21 Jul 2020 08:22:17 +0200 From: Wolfram Sang To: Rob Herring Cc: Alain Volmat , mark.rutland@arm.com, pierre-yves.mordret@st.com, mcoquelin.stm32@gmail.com, alexandre.torgue@st.com, linux-i2c@vger.kernel.org, devicetree@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, fabrice.gasnier@st.com Subject: Re: [PATCH v2 3/4] dt-bindings: i2c-stm32: add SMBus Alert bindings Message-ID: <20200721062217.GA1044@kunai> References: <1593070769-9106-1-git-send-email-alain.volmat@st.com> <1593070769-9106-4-git-send-email-alain.volmat@st.com> <20200630194107.GA999@ninjato> <20200714023048.GA1151665@bogus> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="8t9RHnE3ZwKMSgU+" Content-Disposition: inline In-Reply-To: <20200714023048.GA1151665@bogus> Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org --8t9RHnE3ZwKMSgU+ Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi Rob, > > > The I2C/SMBUS framework already provides a mechanism to enable SMBus-= Alert > > > by naming an IRQ line "smbus_alert". However, on stm32, the SMBus-Ale= rt is > > > part of the i2c IRQ. Using the smbus_alert naming here would lead to = having > > > 2 handlers (the handler of the driver and the smbus_alert handler > > > from I2C/SMBUS framework) on the unique i2c IRQ of the stm32. Meaning= that > > > the smbus_alert handler would get called for all IRQ generated by the= stm32 > > > I2C controller. > > >=20 > > > For that reason, the smbus_alert IRQ naming cannot be used and a dedi= cated > > > binding is introduced. > >=20 > > What if we update the core to not register another irq handler if the > > "smbus_alert" and main irq are the same? > >=20 > > I think it could work. However, while trying to make a proof-of-concept, > > I found that irq descriptions in the generic i2c binding document are > > probably mixed up. And before fixing that, I'd like to get HostNotify > > done first. >=20 > Why does this even need to be in DT? Can't the driver just register that= =20 > it supports SMBus alert or have some call to the core signaling an SMBus= =20 > alert?=20 If we emulate this SMBus behaviour with I2C, it means we apply additional restrictions. In this case, there is an address which can't be used anymore. Because there is another case of additional restrictions, I proposed the binding "smbus" which means this bus is not I2C but SMBus, so it is more restricted. 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