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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 574B6ECAAD5 for ; Mon, 12 Sep 2022 08:01:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229561AbiILIBo (ORCPT ); Mon, 12 Sep 2022 04:01:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34526 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229541AbiILIBl (ORCPT ); Mon, 12 Sep 2022 04:01:41 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 691FF1F601; Mon, 12 Sep 2022 01:01:40 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id D011A61135; Mon, 12 Sep 2022 08:01:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 24907C433D6; Mon, 12 Sep 2022 08:01:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1662969699; bh=v+AyXBUD9DFdJO4omi8QokO6GzLNvBxd3uEkVZ/8+lc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=LHDjion6zLX6cQ6wcj5wAxSgj3FDQYmmQwqgr2gFyy+eTlMzfnhNlWtLM+nMjzDmE pfRKyz9rto5l+qFVwptpivYqsrtajPdX2AlALjnsIe74tA5p0N3TcJMa+z66Gq+Ifw U/uigHOGcMyocfjjV+YRAExbC5k2VjDW6jt2LuSwwRAVxRIdk3JM/tDpZqokJnkzZb +QqGMWJN+sD+5ardPES8MdVIoxn65qjQJVGn6cnriyzG/Z0kpjJ7JmKjWI+361YzEH mEklQz+OVTiNx0hlad2M2TXEwGqSfgE825QVwNM1sgE/hw1liuPODIDSmI7/6NwA1J SoT+4++bS2Maw== Date: Mon, 12 Sep 2022 10:01:32 +0200 From: Lorenzo Pieralisi To: Pali =?iso-8859-1?Q?Roh=E1r?= Cc: Bjorn Helgaas , Bjorn Helgaas , Thomas Petazzoni , Lorenzo Pieralisi , Rob Herring , Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Marc Zyngier Subject: Re: [PATCH] PCI: mvebu: Use devm_request_irq() for registering interrupt handler Message-ID: References: <20220709143151.qhoa7vjcidxadrvt@pali> <20220709234430.GA489657@bhelgaas> <20220710000659.vxmlsvoin26tdiqw@pali> <20220829165109.fzrgguchg4otbbab@pali> <20220911154516.tu2b7qhsnk6mdtui@pali> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220911154516.tu2b7qhsnk6mdtui@pali> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Sun, Sep 11, 2022 at 05:45:16PM +0200, Pali Rohár wrote: > On Monday 29 August 2022 18:51:09 Pali Rohár wrote: > > On Sunday 10 July 2022 02:06:59 Pali Rohár wrote: > > > On Saturday 09 July 2022 18:44:30 Bjorn Helgaas wrote: > > > > [+cc Marc, since he commented on this] > > > > > > > > On Sat, Jul 09, 2022 at 04:31:51PM +0200, Pali Rohár wrote: > > > > > On Friday 01 July 2022 16:29:41 Pali Rohár wrote: > > > > > > On Thursday 23 June 2022 11:27:47 Bjorn Helgaas wrote: > > > > > > > On Tue, May 24, 2022 at 02:28:17PM +0200, Pali Rohár wrote: > > > > > > > > Same as in commit a3b69dd0ad62 ("Revert "PCI: aardvark: Rewrite IRQ code to > > > > > > > > chained IRQ handler"") for pci-aardvark driver, use devm_request_irq() > > > > > > > > instead of chained IRQ handler in pci-mvebu.c driver. > > > > > > > > > > > > > > > > This change fixes affinity support and allows to pin interrupts from > > > > > > > > different PCIe controllers to different CPU cores. > > > > > > > > > > > > > > Several other drivers use irq_set_chained_handler_and_data(). Do any > > > > > > > of them need similar changes? The commit log suggests that using > > > > > > > chained IRQ handlers breaks affinity support. But perhaps that's not > > > > > > > the case and the real culprit is some other difference between mvebu > > > > > > > and the other drivers. > > > > > > > > > > > > And there is another reason to not use irq_set_chained_handler_and_data > > > > > > and instead use devm_request_irq(). Armada XP has some interrupts > > > > > > shared and it looks like that irq_set_chained_handler_and_data() API > > > > > > does not handle shared interrupt sources too. > > > > > > > > > > > > I can update commit message to mention also this fact. > > > > > > > > > > Anything needed from me to improve this fix? > > > > > > > > My impression from Marc's response [1] was that this patch would > > > > "break the contract the kernel has with userspace" and he didn't think > > > > this was acceptable. But maybe I'm not understanding it correctly. > > > > > > This is argument which Marc use when he does not have any argument. > > > > > > Support for dedicated INTx into pci-mvebu.c was introduced just recently > > > and I used irq_set_chained_handler_and_data() just because I thought it > > > is a good idea and did not know about all those issues with it. So there > > > cannot be any breakage by this patch. > > > > > > I already converted other pci-aardvark.c driver to use > > > irq_set_chained_handler_and_data() API because wanted it... But at the > > > end _that conversion_ caused breakage of afinity support and so this > > > conversion had to be reverted: > > > https://lore.kernel.org/linux-pci/20220515125815.30157-1-pali@kernel.org/#t > > > > > > Based on his past decisions, above suggestions which cause _real_ > > > breakage and his expressions like mvebu should be put into the trash, > > > I'm not going to listen him anymore. The only breaking is done by him. > > > > > > > > > There are two arguments why to not use irq_set_chained_handler_and_data: > > > > > > 1) It does not support afinity and therefore has negative performance > > > impact on Armada platforms with more CPUs and more PCIe ports. > > > > > > 2) It does not support shared interrupts and therefore it will break > > > hardware on which interrupt lines are shares (mostly Armada XP). > > > > > > So these issues have to be fixed and currently I see only option to > > > switch irq_set_chained_handler_and_data() to devm_request_irq() which I > > > did in this fixup patch. > > > > Any progress here? This patch is waiting here since end of May and if > > something is going to be broken then it is this fact of ignoring reported > > issues and proposed patch. Do you better solution how to fix commit > > ec075262648f? > > After two weeks I'm reminding this fix patch again... There is no point complaining about something you were asked to change, really - there is not. You were given feedback, feel free to ignore it, it won't help getting this patch upstream - it is as simple as that, sorry. Thanks, Lorenzo