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=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 D8F5CC169C4 for ; Mon, 11 Feb 2019 22:12:12 +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 A57EA218AD for ; Mon, 11 Feb 2019 22:12:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="j/vnMIza" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A57EA218AD Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com 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-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=9qotoN9W8FTgdJWhCDFNSUrIGyCVc2b61gysFEADE1Y=; b=j/vnMIzaccshSg WY7v+u94jFBjj51tO78N64MczCDuCZFSBUrKhxUVTqnedpuCuA345xg98QxdsD5M6EWaD6rCUI2Un jWFHiEgpVMUfm/FCZj+obORaQF/aRIHENIBEc684H0VdX+QpC6HllcwlCi3bGXhKekodIMS/W+btt ZXUFWXtjYmqMjVbiUWVfZ25XzYSEUKTJuW0aEwubWoBszUnZOEvcdw0KTv1lIirdqJL+rnDC1CEBC JLMjD1XgHLCtdU8uTBFlCj0Ve4xb0HVm1PaNYaU4zNmwQinzo5PKX09M/TeM8OrWJULaoH2Rjy2QQ Wlb/praeoM5cfCGLgBtQ==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gtJoA-0004Cf-NM; Mon, 11 Feb 2019 22:12:10 +0000 Received: from foss.arm.com ([217.140.101.70]) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gtJo6-0004BW-LN for linux-arm-kernel@lists.infradead.org; Mon, 11 Feb 2019 22:12:08 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id A64D4EBD; Mon, 11 Feb 2019 14:12:02 -0800 (PST) Received: from why.wild-wind.fr.eu.org (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id CFE4A3F675; Mon, 11 Feb 2019 14:12:00 -0800 (PST) Date: Mon, 11 Feb 2019 22:11:56 +0000 From: Marc Zyngier To: Linus Walleij Subject: Re: [PATCH 04/17 v1] irqchip: Add driver for IXP4xx Message-ID: <20190211221156.10036ad8@why.wild-wind.fr.eu.org> In-Reply-To: References: <20190203214205.13594-1-linus.walleij@linaro.org> <20190203214205.13594-5-linus.walleij@linaro.org> Organization: ARM Ltd X-Mailer: Claws Mail 3.14.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190211_141206_704841_5152CAA8 X-CRM114-Status: GOOD ( 24.68 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jason Cooper , Arnd Bergmann , Tim Harvey , Krzysztof Halasa , Olof Johansson , Thomas Gleixner , Imre Kaloz , Linux ARM Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, 11 Feb 2019 21:58:41 +0100 Linus Walleij wrote: > On Mon, Feb 11, 2019 at 4:30 PM Marc Zyngier wrote: [...] > > How about using something that enforces the endianness of the accesses, > > as I suspect the bus is hardcoded to BE? > > So, IIUC (Krzysztof can confirm) IXP4xx works like this that when the > CPU is brought up in LE mode, all bytes on the address bus are > swizzled so that the access can always use the CPU native > endianness. > > Isn't it crazy :D It's spelled BE32! ;-) I vaguely remember doing some of that on vulcan, but that's a decade ago, and I've paged it out... ;-) > This means __raw_writel() will always do the right thing, because > that uses native endianness, and that is why it is used quite a lot > in IXP4xx drivers. OK, it now makes some sense. Maybe a comment somewhere will help if someone tries to reverse engineer it again in the next decade! > > Aren't you guaranteed to only have one such irqchip? If so, this could > > become a static const object, instead of allocating it dynamically. Not > > a big deal though. > > Force of habit. Comes from the GPIO side of things where we > never know how many instances there are of stuff, if it's OK > I'd like to keep it. No problem. > > > > + fwnode = irq_domain_alloc_fwnode(base); > > > > I assume this is a temporary solution until the SoC gains a DT port (and > > the irqchip a DT node)? > > Yes, see the later DT patch that passes the parent as > fwnode, once all boards are converted we can drop this. > > BTW here is how I then use the hierarchical parent in the > GPIO chip: > https://marc.info/?l=linux-arm-kernel&m=154923023907623&w=2 > https://marc.info/?l=linux-arm-kernel&m=154923038707686&w=2 Looks pretty cool, and surely even better once entirely converted to DT (I'm sure I can revive this FSG-3 that has been collecting dust on the shelf for a number of years). Please CC me on the whole series next time you respin it! Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel