From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x225QtcB9m1ZSYw8IiF3QiETsT0KaaeotkIOFrHMsew+ReHa4q4uV2odw39nREItQ4X77HDst ARC-Seal: i=1; a=rsa-sha256; t=1519766061; cv=none; d=google.com; s=arc-20160816; b=M2SCgzr4GfV3cZzmbJOgqEGZtd+CPS3BG2tjO40BmURW2g64FUsR5s2XclCY+pevnE iM0XbQVY11QHF5Vk1GWPOTkNJALalThN4y6bjUPv+dFMUscqYuyIP1ySUIDhDIPZD6KE X4obaiuZVPEmbx7769Ql/NQXoD6NCmYiHeDNN+iJpMDLezc8C4vA4CWsuk3tRxTsSnbG JWhe7l5dm7eH+vGJFsgtkP5fncjLG2pNeVJZtLl9lrk/VfBlnbUcpFt0R9Fdmx6ceXGu IGIKbYl3WQmaPDx6L/hkFm/ND4AGCOeDL410BVUh7Iy6JFel525WTUTl+3k4Ns7S6OLU FxTA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:arc-authentication-results; bh=/5EEkiYp/JNtvF0KVtm4VwXNFcxMQTZ5m1a94lu0UtU=; b=NXi3M9qXMb0ly8ZOgHmDTzSBvGv1S6myEhMm5BDVH/vZ8W46RwM8Xyi1a3PjIc/zv/ /LJnJPrUL8XrBU+2dhYpYknNWNWPVZsZuIXEOt+XM1+aKeHrpvYf9mB+/aNJuDrXPIuR dT8fzb6cr9LzEtA826KLZWWY6cSUTIAz0fuBaMsPH0sDb9jPJaQmAE1EzLAvTm4mpvSI 5k7PEzTEttNUlnk0J++1AZ2TSlTSZlrL1kigp4FsCtcbIjKJlxeQWM9vg6gICYYHUluz jmIjrRizBujXZ+uTiF1DlvowJKt/3h8Dtaop8NG79NifOmHTzx9jbOlIDWIe+Ylb6Yer JQOQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of boris.brezillon@bootlin.com designates 62.4.15.54 as permitted sender) smtp.mailfrom=boris.brezillon@bootlin.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of boris.brezillon@bootlin.com designates 62.4.15.54 as permitted sender) smtp.mailfrom=boris.brezillon@bootlin.com Date: Tue, 27 Feb 2018 22:14:07 +0100 From: Boris Brezillon To: Przemyslaw Sroka Cc: Vitor Soares , Boris Brezillon , Wolfram Sang , "linux-i2c@vger.kernel.org" , Jonathan Corbet , "linux-doc@vger.kernel.org" , Greg Kroah-Hartman , Arnd Bergmann , Arkadiusz Golec , Alan Douglas , Bartosz Folta , Damian Kos , Alicja Jurasik-Urbaniak , Cyprian Wronka , Suresh Punnoose , Thomas Petazzoni , Nishanth Menon , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Geert Uytterhoeven , Linus Walleij Subject: Re: [PATCH v2 2/7] i3c: Add core I3C infrastructure Message-ID: <20180227221407.0cd7f8a9@bbrezillon> In-Reply-To: References: <20171214151610.19153-1-boris.brezillon@free-electrons.com> <20171214151610.19153-3-boris.brezillon@free-electrons.com> <20180223213000.407461d2@bbrezillon> <1b8fe82f-079b-6f55-0e59-5773027faa8e@synopsys.com> <20180226213607.7161bb0a@bbrezillon> <20180227211302.26f76427@bbrezillon> X-Mailer: Claws Mail 3.15.0-dirty (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1586772916728163872?= X-GMAIL-MSGID: =?utf-8?q?1593590217389235534?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Tue, 27 Feb 2018 20:24:43 +0000 Przemyslaw Sroka wrote: > > > SETDASA is simply faster than ENTDAA, but only if there is no > > > need to collect BCR/DCR/PID of such devices. I think most > > > applications would like to have them as an status information so > > > after all ENTDAA can be regarded as an generic approach (unless > > > I'm mistaken). > > > > Actually, we could retrieve BCR/DCR/PID (and all other relevant > > information, like MAXDS) even with the SETDASA approach. We just > > need to send the according CCC commands after SETDASA. > > > I agree, what I meant by "SETDASA is simply faster than ENTDAA, but > only if there is no need to collect BCR/DCR/PID of such devices." Is > that it is faster than DAA but only if not followed by GET CCC > commands to gather BCR/DCR/PID. I think we are on the same page here. Yes, but right now it's not the case, see my other reply ;-). > > > But that's also my understanding that ENTDAA should always work, and > > SETDASA usage is only needed if you want to reserve a dynamic > > address and assign it to a device before DAA takes place. This way > > you can enforce the device priority (WRT IBIs). But honestly, > > that's the only use case I can think of, and to me, it sounds like > > an advanced feature we may want to support at some point, but don't > > need in the initial implementation. > Still ENTDAA seems to be sufficient for IBI prioritization but I can > imagine some use cases where people would like to use it for such > purposes. Note that SETDASA is applicable only for devices with SA so > it is self-explanatory that it cannot be considered as utility to > define priorities for all devices before ENTDAA. We have SETNEWDA for other use cases: say you want one of your device to have an higher priority, you can just manually set a new dynamic address that is lower than any other devices on the bus (I plan to expose that through sysfs, by making the address file writable). -- Boris Brezillon, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com