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=-4.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,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 D1141C4338F for ; Mon, 23 Aug 2021 09:35:51 +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 9A767613A1 for ; Mon, 23 Aug 2021 09:35:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 9A767613A1 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Subject:Cc:To:From:Message-ID:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=T7kvktOHfgBWPzNSj6exXHE7E/ZR5W6G5gUQT1mUr6E=; b=3KbsfTAdmLKkkw ycuWRWTIOYzbVlrktlD9NcWVpuWkh5kzORDjuTZeWSdpJdrGWEt2nb/A6Ggq+VIDPDJ2KttXSWC2s wblD6dBdwRKjh15+jSQ6YxaZ6us4rvODg0efG/PelioyeqKZ+2EgdTDPtHpQB1SPkr30V0IiHdHX9 Cv4WBdnbLlgR+zUdhefUdKJRJsXq6t9QrXdpGz+CZhlR7rAYkNrwDPX/mHA/xJDi78gZRI1RwBZ5h 9PyuLuD60IyddTglIRp34inWDCFCjVc/Fo+ihpcy4D1RuK++k6ICkKu+L5hR9ocgFoM0NtNpx04jy 0X0M1J3Dchs0dDE7ueBw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mI6Kx-00G9Mv-IK; Mon, 23 Aug 2021 09:33:47 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mI6Kt-00G9Ly-48 for linux-arm-kernel@lists.infradead.org; Mon, 23 Aug 2021 09:33:44 +0000 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (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 7C1486137F; Mon, 23 Aug 2021 09:33:42 +0000 (UTC) Received: from sofa.misterjones.org ([185.219.108.64] helo=why.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1mI6Kq-006cqm-GD; Mon, 23 Aug 2021 10:33:40 +0100 Date: Mon, 23 Aug 2021 10:33:40 +0100 Message-ID: <87czq4qzd7.wl-maz@kernel.org> From: Marc Zyngier To: Valentin Schneider Cc: Guenter Roeck , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] irqchip/gic: Convert to handle_strict_flow_irq() In-Reply-To: <878s0t6s7p.mognet@arm.com> References: <20210814194737.GA3951530@roeck-us.net> <87sfzb7jeo.mognet@arm.com> <87eeav19mc.wl-maz@kernel.org> <87k0kk7w0c.mognet@arm.com> <87czqasn9u.wl-maz@kernel.org> <878s0t6s7p.mognet@arm.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.1 (x86_64-pc-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: valentin.schneider@arm.com, linux@roeck-us.net, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210823_023343_235808_1210628D X-CRM114-Status: GOOD ( 32.03 ) 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="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Sun, 22 Aug 2021 23:16:10 +0100, Valentin Schneider wrote: > > On 18/08/21 17:58, Marc Zyngier wrote: > > On Tue, 17 Aug 2021 01:30:43 +0100, > > Valentin Schneider wrote: > >> Are we guaranteed to have > >> > >> .irq_ack \in {NULL, irq_chip_ack_parent} > >> > >> for all intermediate (!root) irqchips? I don't see why that wouldn't > >> be the case, and with that in mind what you described makes sense to > >> me. > > > > An intermediate layer is allowed to implement its own irq_ack that is > > not irq_chip_ack_parent, but it then has to call irq_chip_ack_parent > > itself. > > > > Right, makes sense. > > > There is the bizarre case of drivers/gpio/gpio-thunderx.c that changes > > the irqchip flow to use either handle_fasteoi_ack_irq or > > handle_fasteoi_mask_irq, which won't play very nicely with this. > > Someone said Cavium? > > > > Humph... > > I'm not familiar at all with the gpiolib irqchips, but I was under the > impression those would involve chained IRQs (it does appear to be the case > for the pl061 GPIOs on a Juno). For those, the innermost desc would be handled > via chained_irq_{enter, exit}() [!!!], and the outermost one via whatever > flow was installed by the relevant driver. Not all of them are built like this. There is actually a bunch of these build as full hierarchies (QC, nvidia and some others). > I can't easily grok what goes on between that gpio-thunderx.c driver and > gpiolib, but since that GPIO chip has > > .irq_eoi = irq_chip_eoi_parent, > > and > > girq->parent_domain = > irq_get_irq_data(txgpio->msix_entries[0].vector)->domain; > > (GPIOs hooked to MSI-X? Do I want to know?) It's good, isn't it? TX1 has all its HW appearing as PCI, even if it clearly isn't PCI underneath. > > I'm guessing it is *not* chained, which means the irq_set_handler_locked() > affects the entire stack :/ It does. We can probably fix that, but I won't be able to test (my TX1 was taken away a few months ago...). I'll accept body donations, for scientific purposes. > > [!!!] Speaking of chained IRQs, I'm now thinking this series breaks them; > chained_irq_enter() + chained_irq_exit() will only issue an ->irq_eoi(), > skipping the ->irq_ack()... One more thing to add to the list! Urghh... Yeah, that's awful. 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