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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 C09C5C4332D for ; Tue, 9 Mar 2021 11:15:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AB5B26525F for ; Tue, 9 Mar 2021 11:15:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229881AbhCILPD (ORCPT ); Tue, 9 Mar 2021 06:15:03 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44432 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229875AbhCILOk (ORCPT ); Tue, 9 Mar 2021 06:14:40 -0500 Received: from mail-lj1-x230.google.com (mail-lj1-x230.google.com [IPv6:2a00:1450:4864:20::230]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 781AFC061762 for ; Tue, 9 Mar 2021 03:14:36 -0800 (PST) Received: by mail-lj1-x230.google.com with SMTP id h4so20127585ljl.0 for ; Tue, 09 Mar 2021 03:14:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=cKjwO43AjsBJoUH6JaO2Y5XWi3uHramUf/9ys8jvzbs=; b=IUkDYmdXyRJ+5eqh5KaFAAav9I7fgeq5aJkWK2UclTqJ3DaNd+VsjtR5q06fui9WXK vf1b4BTQklr/p9t2OGjzoduMVlfBvwaj3ZUXvEqaVil5eQ58ERriPFCI1276Lsm6E6Qs znM0/daP+ANcymrxL2HJMHsf3oYJryKxg26zlCQD+Kc2UQQmxQgGPEgsVc9cbkWUrJM5 OY1THL0sfTB7KwJoDZEP4MEuBBMsFX/hYfnG4jbPcM1l0OR8uWhn+3csn+h8lstYLR97 aVaZd1sB5lMIEo3EID8BZM1zBgsfWLRilssJzwaU/hlIgt7TkVBHy9cXXDdV2y5bNAzU 5P0Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=cKjwO43AjsBJoUH6JaO2Y5XWi3uHramUf/9ys8jvzbs=; b=BHP15HrwPtWdXq8eHnmtiblGnsL8EA77yH3WblYcylpxEE8pqIdgV0d01yjVmb3+W9 67lfGcS6TR1Kh2OifKsDFZ4aa9u/Cw+ia3JuOoO/fu6Yo8txfxa54fsgL7jYt6S7Iawr yG7mRL2AoRAQhO3iLyFe3W0gU00ftNLXp6Ns5+MNKYsBi6y9xKK9pZv6LscJ5JYFo7xw 1PrTQPi8FcqC5rhzGU/h8z5iPoqWd8gT1xXqzDLnQxf7nT1Hv7HP22qBspw0wnDapte/ YnOUGaPTIkGAKCXdd3qEcTeLzKgsyLqsPYmkp9k4DOG4XjvlvAfoNc7rnyW5MYyTHxcJ /JtQ== X-Gm-Message-State: AOAM531iRSqGaZQzZP+RDViNDTyq/6V8nrgSbXukdtw0zz8ydBizeDvS 8XKAYbpcgnJ0YG5YoynOzMG+YVUDR2elf3W0QAAr4w== X-Google-Smtp-Source: ABdhPJxUU43eMEhovgOv2iI7axC0yDatB6+NKL+zAY6DqrP12n8/hW5rse6yj9rlUf5G+F44LP2/X+q/+bxXKVOpV4k= X-Received: by 2002:a2e:7001:: with SMTP id l1mr16537048ljc.200.1615288474745; Tue, 09 Mar 2021 03:14:34 -0800 (PST) MIME-Version: 1.0 References: <20210304213902.83903-1-marcan@marcan.st> <20210304213902.83903-13-marcan@marcan.st> <6e4880b3-1fb6-0cbf-c1a5-7a46fd9ccf62@marcan.st> <20210308211306.GA2920998@robh.at.kernel.org> In-Reply-To: <20210308211306.GA2920998@robh.at.kernel.org> From: Linus Walleij Date: Tue, 9 Mar 2021 12:14:23 +0100 Message-ID: Subject: Re: [RFT PATCH v3 12/27] of/address: Add infrastructure to declare MMIO as non-posted To: Rob Herring Cc: Arnd Bergmann , Hector Martin , linux-arm-kernel , Marc Zyngier , Olof Johansson , Krzysztof Kozlowski , Mark Kettenis , Tony Lindgren , Mohamed Mediouni , Stan Skowronek , Alexander Graf , Will Deacon , Mark Rutland , Andy Shevchenko , Greg Kroah-Hartman , Jonathan Corbet , Catalin Marinas , Christoph Hellwig , "David S. Miller" , DTML , "open list:SERIAL DRIVERS" , Linux Doc Mailing List , linux-samsung-soc , "open list:GENERIC INCLUDE/ASM HEADER FILES" , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 8, 2021 at 10:13 PM Rob Herring wrote: > On Mon, Mar 08, 2021 at 09:29:54PM +0100, Arnd Bergmann wrote: > > This is obviously more work for the drivers, but at least it keeps > > the common code free of the hack while also allowing drivers to > > use ioremap_np() intentionally on other platforms. > > I don't agree. The problem is within the interconnect. The device and > its driver are unaware of this. If it is possible that a driver needs to use posted access on one SoC and nonposted on another SoC then clearly the nature of the access need to be part of the memory access abstraction, obviously ioremap() one way or another. Having the driver conditionally use different ioremap_* functions depending on SoC seems awkward. We had different execution paths for OF and ACPI drivers and have been working hard to create fwnode to abstract this away for drivers used with both abstractions for example. If we can hide it from drivers from day 1 I think we can save maintenance costs in the long run. Given that the Apple silicon through it's heritage from Samsung S3C (the genealogy is unclear to me) already share drivers with this platform, this seems to already be the case so it's not a theoretical use case. The core argument here seems to be "will this become common practice or is it an Apple-ism?" That is a question to someone who is deep down there synthesizing SoCs. It appears the market for custom silicon laptops has just begun. There are people that can answer this question but I doubt that we have access to them or that they would tell us. What is an educated guess? It seems Arnds position is that it's an Apple-ism and I kind of trust him on this. At the same time I know that in emerging markets, what copycats are likely to do is say "give me exactly what Apple has, exactly that thing". Just my =E2=82=AC0.01 Linus Walleij 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=-4.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 98033C433E0 for ; Tue, 9 Mar 2021 11:16:18 +0000 (UTC) Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 3404F65253 for ; Tue, 9 Mar 2021 11:16:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3404F65253 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linaro.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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=desiato.20200630; h=Sender:Content-Transfer-Encoding :Content-Type:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:Cc:To:Subject:Message-ID:Date:From:In-Reply-To: References:MIME-Version:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=FiJwgHKXjXdIfpAZ/n+SsLiM/lpWwIr84+UO7KLcXx4=; b=Pp6rJe5U585dEXPr1qGfUuoJB cgbsxYCpnNYOg27WcSYHIE1IunHCxvMFR1D0PSix6aIAuYjIn85QYCLLCrbys5obQKPCR7tL53qlQ A08dzJQvN4EzKT/sacTdzUwSARa4t42Hrf2lNDakWBK0CVYyrVifTTnLD8Q5qCg3geb0xGuLLb/Sd D8nJqWyJ0Xg8UsUnNHx0E8GhNY5zk72Xlrd7u7QVaR/SRaScw5EO2KJ5Mo7lSuzRHPkJWlCaAsPTO yYElOPhNCYwdEkHV5B9QtkrKiWSpDuPcd8jqKAFQPs7DXyURFoyjvCNplM1GgqX9cEkHaQcFyzLi8 1mLCjEHDA==; Received: from localhost ([::1] helo=desiato.infradead.org) by desiato.infradead.org with esmtp (Exim 4.94 #2 (Red Hat Linux)) id 1lJaK3-004Gz4-NU; Tue, 09 Mar 2021 11:14:43 +0000 Received: from mail-lj1-x22c.google.com ([2a00:1450:4864:20::22c]) by desiato.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lJaJw-004Gxo-Ez for linux-arm-kernel@lists.infradead.org; Tue, 09 Mar 2021 11:14:38 +0000 Received: by mail-lj1-x22c.google.com with SMTP id t9so20084772ljt.8 for ; Tue, 09 Mar 2021 03:14:35 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=cKjwO43AjsBJoUH6JaO2Y5XWi3uHramUf/9ys8jvzbs=; b=IUkDYmdXyRJ+5eqh5KaFAAav9I7fgeq5aJkWK2UclTqJ3DaNd+VsjtR5q06fui9WXK vf1b4BTQklr/p9t2OGjzoduMVlfBvwaj3ZUXvEqaVil5eQ58ERriPFCI1276Lsm6E6Qs znM0/daP+ANcymrxL2HJMHsf3oYJryKxg26zlCQD+Kc2UQQmxQgGPEgsVc9cbkWUrJM5 OY1THL0sfTB7KwJoDZEP4MEuBBMsFX/hYfnG4jbPcM1l0OR8uWhn+3csn+h8lstYLR97 aVaZd1sB5lMIEo3EID8BZM1zBgsfWLRilssJzwaU/hlIgt7TkVBHy9cXXDdV2y5bNAzU 5P0Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=cKjwO43AjsBJoUH6JaO2Y5XWi3uHramUf/9ys8jvzbs=; b=PQwWih/rm3esaxyrsgVfCI4dpFQM1tMvNh6JmliP/1vxtKTr+JQ8ro5XMm8ETbIlhP lZARaCEKliJ/QKNBV1l4XiuYqDuvUr1zwe4JgoE0rCIItMgiulRmHogH4VrvvXUeonbg 58IxkWcepK1OAAH4RrTifvy5a3gTVw2ADehizKAS5nzges3+ApbCN+E/uFPHMTAscP2q pUGocrwISk3rjSUCF16jU/Rc9mBm+ZsVk0XhR6AKvcV/FNdIBCJFb8odPQNuuxBnM99A ACkrUIbwCGWmeVguW3lthKAjxtJQ+Lpb/Rdy/K9x55XPPAzV/A5YTmQCFcc45pgr8lrI C7vA== X-Gm-Message-State: AOAM532frzYheNGCe1G9oYZn9cWmrkyc8LOqNmLAvzEYB8Ba4lI0WFEf Dc2bbmX/gwwW8TEZKp+qviL0SKb7TzAw3R9RdpkUeQ== X-Google-Smtp-Source: ABdhPJxUU43eMEhovgOv2iI7axC0yDatB6+NKL+zAY6DqrP12n8/hW5rse6yj9rlUf5G+F44LP2/X+q/+bxXKVOpV4k= X-Received: by 2002:a2e:7001:: with SMTP id l1mr16537048ljc.200.1615288474745; Tue, 09 Mar 2021 03:14:34 -0800 (PST) MIME-Version: 1.0 References: <20210304213902.83903-1-marcan@marcan.st> <20210304213902.83903-13-marcan@marcan.st> <6e4880b3-1fb6-0cbf-c1a5-7a46fd9ccf62@marcan.st> <20210308211306.GA2920998@robh.at.kernel.org> In-Reply-To: <20210308211306.GA2920998@robh.at.kernel.org> From: Linus Walleij Date: Tue, 9 Mar 2021 12:14:23 +0100 Message-ID: Subject: Re: [RFT PATCH v3 12/27] of/address: Add infrastructure to declare MMIO as non-posted To: Rob Herring Cc: Arnd Bergmann , Hector Martin , linux-arm-kernel , Marc Zyngier , Olof Johansson , Krzysztof Kozlowski , Mark Kettenis , Tony Lindgren , Mohamed Mediouni , Stan Skowronek , Alexander Graf , Will Deacon , Mark Rutland , Andy Shevchenko , Greg Kroah-Hartman , Jonathan Corbet , Catalin Marinas , Christoph Hellwig , "David S. Miller" , DTML , "open list:SERIAL DRIVERS" , Linux Doc Mailing List , linux-samsung-soc , "open list:GENERIC INCLUDE/ASM HEADER FILES" , "linux-kernel@vger.kernel.org" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210309_111436_612233_0A503B48 X-CRM114-Status: GOOD ( 21.51 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gTW9uLCBNYXIgOCwgMjAyMSBhdCAxMDoxMyBQTSBSb2IgSGVycmluZyA8cm9iaEBrZXJuZWwu b3JnPiB3cm90ZToKPiBPbiBNb24sIE1hciAwOCwgMjAyMSBhdCAwOToyOTo1NFBNICswMTAwLCBB cm5kIEJlcmdtYW5uIHdyb3RlOgoKPiA+IFRoaXMgaXMgb2J2aW91c2x5IG1vcmUgd29yayBmb3Ig dGhlIGRyaXZlcnMsIGJ1dCBhdCBsZWFzdCBpdCBrZWVwcwo+ID4gdGhlIGNvbW1vbiBjb2RlIGZy ZWUgb2YgdGhlIGhhY2sgd2hpbGUgYWxzbyBhbGxvd2luZyBkcml2ZXJzIHRvCj4gPiB1c2UgaW9y ZW1hcF9ucCgpIGludGVudGlvbmFsbHkgb24gb3RoZXIgcGxhdGZvcm1zLgo+Cj4gSSBkb24ndCBh Z3JlZS4gVGhlIHByb2JsZW0gaXMgd2l0aGluIHRoZSBpbnRlcmNvbm5lY3QuIFRoZSBkZXZpY2Ug YW5kCj4gaXRzIGRyaXZlciBhcmUgdW5hd2FyZSBvZiB0aGlzLgoKSWYgaXQgaXMgcG9zc2libGUg dGhhdCBhIGRyaXZlciBuZWVkcyB0byB1c2UgcG9zdGVkIGFjY2VzcyBvbiBvbmUKU29DIGFuZCBu b25wb3N0ZWQgb24gYW5vdGhlciBTb0MgdGhlbiBjbGVhcmx5IHRoZSBuYXR1cmUKb2YgdGhlIGFj Y2VzcyBuZWVkIHRvIGJlIHBhcnQgb2YgdGhlIG1lbW9yeSBhY2Nlc3MgYWJzdHJhY3Rpb24sCm9i dmlvdXNseSBpb3JlbWFwKCkgb25lIHdheSBvciBhbm90aGVyLgoKSGF2aW5nIHRoZSBkcml2ZXIg Y29uZGl0aW9uYWxseSB1c2UgZGlmZmVyZW50IGlvcmVtYXBfKgpmdW5jdGlvbnMgZGVwZW5kaW5n IG9uIFNvQyBzZWVtcyBhd2t3YXJkLiBXZSBoYWQgZGlmZmVyZW50CmV4ZWN1dGlvbiBwYXRocyBm b3IgT0YgYW5kIEFDUEkgZHJpdmVycyBhbmQgaGF2ZSBiZWVuIHdvcmtpbmcKaGFyZCB0byBjcmVh dGUgZndub2RlIHRvIGFic3RyYWN0IHRoaXMgYXdheSBmb3IgZHJpdmVycyB1c2VkIHdpdGgKYm90 aCBhYnN0cmFjdGlvbnMgZm9yIGV4YW1wbGUuIElmIHdlIGNhbiBoaWRlIGl0IGZyb20gZHJpdmVy cwpmcm9tIGRheSAxIEkgdGhpbmsgd2UgY2FuIHNhdmUgbWFpbnRlbmFuY2UgY29zdHMgaW4gdGhl IGxvbmcKcnVuLgoKR2l2ZW4gdGhhdCB0aGUgQXBwbGUgc2lsaWNvbiB0aHJvdWdoIGl0J3MgaGVy aXRhZ2UgZnJvbSBTYW1zdW5nClMzQyAodGhlIGdlbmVhbG9neSBpcyB1bmNsZWFyIHRvIG1lKSBh bHJlYWR5IHNoYXJlIGRyaXZlcnMgd2l0aAp0aGlzIHBsYXRmb3JtLCB0aGlzIHNlZW1zIHRvIGFs cmVhZHkgYmUgdGhlIGNhc2Ugc28gaXQncyBub3QgYQp0aGVvcmV0aWNhbCB1c2UgY2FzZS4KClRo ZSBjb3JlIGFyZ3VtZW50IGhlcmUgc2VlbXMgdG8gYmUgIndpbGwgdGhpcyBiZWNvbWUgY29tbW9u CnByYWN0aWNlIG9yIGlzIGl0IGFuIEFwcGxlLWlzbT8iCgpUaGF0IGlzIGEgcXVlc3Rpb24gdG8g c29tZW9uZSB3aG8gaXMgZGVlcCBkb3duIHRoZXJlCnN5bnRoZXNpemluZyBTb0NzLiBJdCBhcHBl YXJzIHRoZSBtYXJrZXQgZm9yIGN1c3RvbSBzaWxpY29uCmxhcHRvcHMgaGFzIGp1c3QgYmVndW4u IFRoZXJlIGFyZSBwZW9wbGUgdGhhdCBjYW4gYW5zd2VyIHRoaXMKcXVlc3Rpb24gYnV0IEkgZG91 YnQgdGhhdCB3ZSBoYXZlIGFjY2VzcyB0byB0aGVtIG9yIHRoYXQgdGhleQp3b3VsZCB0ZWxsIHVz LiBXaGF0IGlzIGFuIGVkdWNhdGVkIGd1ZXNzPyBJdCBzZWVtcyBBcm5kcwpwb3NpdGlvbiBpcyB0 aGF0IGl0J3MgYW4gQXBwbGUtaXNtIGFuZCBJIGtpbmQgb2YgdHJ1c3QgaGltIG9uIHRoaXMuCkF0 IHRoZSBzYW1lIHRpbWUgSSBrbm93IHRoYXQgaW4gZW1lcmdpbmcgbWFya2V0cywgd2hhdApjb3B5 Y2F0cyBhcmUgbGlrZWx5IHRvIGRvIGlzIHNheSAiZ2l2ZSBtZSBleGFjdGx5IHdoYXQgQXBwbGUK aGFzLCBleGFjdGx5IHRoYXQgdGhpbmciLgoKSnVzdCBteSDigqwwLjAxCkxpbnVzIFdhbGxlaWoK Cl9fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCmxpbnV4LWFy bS1rZXJuZWwgbWFpbGluZyBsaXN0CmxpbnV4LWFybS1rZXJuZWxAbGlzdHMuaW5mcmFkZWFkLm9y ZwpodHRwOi8vbGlzdHMuaW5mcmFkZWFkLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2xpbnV4LWFybS1r ZXJuZWwK