From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Rosin Subject: Re: [PATCH v6 00/10] Add the I3C subsystem Date: Fri, 20 Jul 2018 12:39:37 +0200 Message-ID: <1a2b7588-9c2e-a25c-6bae-5c8c8675667e@axentia.se> References: <20180719152930.3715-1-boris.brezillon@bootlin.com> <2ab0ab75-2df0-2714-f007-c33b25481016@axentia.se> <20180720120518.445b947b@bbrezillon> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180720120518.445b947b@bbrezillon> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Boris Brezillon Cc: Arnd Bergmann , Wolfram Sang , linux-i2c@vger.kernel.org, Jonathan Corbet , "open list:DOCUMENTATION" , Greg Kroah-Hartman , Przemyslaw Sroka , Arkadiusz Golec , Alan Douglas , Bartosz Folta , Damian Kos , Alicja Jurasik-Urbaniak , Cyprian Wronka , Suresh Punnoose , Rafal Ciepiela , Thomas Petazzoni , Nishanth Menon , Rob Herring , Pawel Moll , Mark Rutland , Ian List-Id: linux-gpio@vger.kernel.org On 2018-07-20 12:05, Boris Brezillon wrote: > On Fri, 20 Jul 2018 11:57:56 +0200 Peter Rosin wrote: >> Maybe a bit-bang I3C master isn't feasible for some fundamental >> reason? > > No, it's clearly not. The way an I3C master is supposed to switch from > open-drain to push-pull during a transaction or the concept of IBIs > are the first things that come to mind, but I guess you have plenty of > other reasons preventing you from implementing a i3c-bit-bang master. Why can't a bit-banger switch from open-drain to push-pull? That's just a matter of disconnecting some pull-ups, no? And maybe you know that no device on your bus uses IBIs? Maybe none of reasons for why bit-banging isn't feasible are applicable? I.e. maybe there can be a I3C bit-banger that perhaps isn't generic and isn't full-featured, but does work just fine in some specific setup? Cheers, Peter 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=-0.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED 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 9D035ECDFBB for ; Fri, 20 Jul 2018 10:40:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 367BF20661 for ; Fri, 20 Jul 2018 10:40:40 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=axentia.se header.i=@axentia.se header.b="gvIQRk5b" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 367BF20661 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=axentia.se Authentication-Results: mail.kernel.org; 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Fri, 20 Jul 2018 10:39:40 +0000 Subject: Re: [PATCH v6 00/10] Add the I3C subsystem To: Boris Brezillon Cc: Arnd Bergmann , Wolfram Sang , linux-i2c@vger.kernel.org, Jonathan Corbet , "open list:DOCUMENTATION" , Greg Kroah-Hartman , Przemyslaw Sroka , Arkadiusz Golec , Alan Douglas , Bartosz Folta , Damian Kos , Alicja Jurasik-Urbaniak , Cyprian Wronka , Suresh Punnoose , Rafal Ciepiela , Thomas Petazzoni , Nishanth Menon , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , DTML , Linux Kernel Mailing List , Vitor Soares , Geert Uytterhoeven , Linus Walleij , Xiang Lin , linux-gpio@vger.kernel.org, Sekhar Nori , Przemyslaw Gaj References: <20180719152930.3715-1-boris.brezillon@bootlin.com> <2ab0ab75-2df0-2714-f007-c33b25481016@axentia.se> <20180720120518.445b947b@bbrezillon> From: Peter Rosin Organization: Axentia Technologies AB Message-ID: <1a2b7588-9c2e-a25c-6bae-5c8c8675667e@axentia.se> Date: Fri, 20 Jul 2018 12:39:37 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; 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The way an I3C master is supposed to switch from > open-drain to push-pull during a transaction or the concept of IBIs > are the first things that come to mind, but I guess you have plenty of > other reasons preventing you from implementing a i3c-bit-bang master. Why can't a bit-banger switch from open-drain to push-pull? That's just a matter of disconnecting some pull-ups, no? And maybe you know that no device on your bus uses IBIs? Maybe none of reasons for why bit-banging isn't feasible are applicable? I.e. maybe there can be a I3C bit-banger that perhaps isn't generic and isn't full-featured, but does work just fine in some specific setup? Cheers, Peter From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-5.6 required=5.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, T_DKIM_INVALID autolearn=ham autolearn_force=no version=3.4.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id 545B97D072 for ; Fri, 20 Jul 2018 10:40:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727410AbeGTL2Q (ORCPT ); Fri, 20 Jul 2018 07:28:16 -0400 Received: from mail-eopbgr50098.outbound.protection.outlook.com ([40.107.5.98]:54929 "EHLO EUR03-VE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727216AbeGTL2P (ORCPT ); Fri, 20 Jul 2018 07:28:15 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=axentia.se; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=BEes1lQ8OmPFZjn9yL0bt/fI5c7bFfZ5l5BzsBz+1Nk=; b=gvIQRk5bv85kO8uFkVU766T2VlxS+LuNQpqlxKlCAyFRj4Uc0hKEUlwSTrJVmD0OJH8fTx90gA/Tzosete/U3dbW4clutK5Yb+TU4qVC8CyZ5A5gnqDXZ1r8w9UPudM1rFBXO4pMPvcwF/GE+jsJg5huzVAx7PXmtbrJYFB0cX8= Authentication-Results: spf=none (sender IP is ) smtp.mailfrom=peda@axentia.se; Received: from [192.168.13.3] (85.226.244.23) by HE1PR0201MB2459.eurprd02.prod.outlook.com (2603:10a6:3:82::7) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.973.16; Fri, 20 Jul 2018 10:39:40 +0000 Subject: Re: [PATCH v6 00/10] Add the I3C subsystem To: Boris Brezillon Cc: Arnd Bergmann , Wolfram Sang , linux-i2c@vger.kernel.org, Jonathan Corbet , "open list:DOCUMENTATION" , Greg Kroah-Hartman , Przemyslaw Sroka , Arkadiusz Golec , Alan Douglas , Bartosz Folta , Damian Kos , Alicja Jurasik-Urbaniak , Cyprian Wronka , Suresh Punnoose , Rafal Ciepiela , Thomas Petazzoni , Nishanth Menon , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , DTML , Linux Kernel Mailing List , Vitor Soares , Geert Uytterhoeven , Linus Walleij , Xiang Lin , linux-gpio@vger.kernel.org, Sekhar Nori , Przemyslaw Gaj References: <20180719152930.3715-1-boris.brezillon@bootlin.com> <2ab0ab75-2df0-2714-f007-c33b25481016@axentia.se> <20180720120518.445b947b@bbrezillon> From: Peter Rosin Organization: Axentia Technologies AB Message-ID: <1a2b7588-9c2e-a25c-6bae-5c8c8675667e@axentia.se> Date: Fri, 20 Jul 2018 12:39:37 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; 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The way an I3C master is supposed to switch from > open-drain to push-pull during a transaction or the concept of IBIs > are the first things that come to mind, but I guess you have plenty of > other reasons preventing you from implementing a i3c-bit-bang master. Why can't a bit-banger switch from open-drain to push-pull? That's just a matter of disconnecting some pull-ups, no? And maybe you know that no device on your bus uses IBIs? Maybe none of reasons for why bit-banging isn't feasible are applicable? I.e. maybe there can be a I3C bit-banger that perhaps isn't generic and isn't full-featured, but does work just fine in some specific setup? Cheers, Peter -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html