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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 AC7FAC31E45 for ; Thu, 13 Jun 2019 16:55:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8BC2F20665 for ; Thu, 13 Jun 2019 16:55:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389983AbfFMQzb (ORCPT ); Thu, 13 Jun 2019 12:55:31 -0400 Received: from gate.crashing.org ([63.228.1.57]:32774 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729999AbfFMCDU (ORCPT ); Wed, 12 Jun 2019 22:03:20 -0400 Received: from localhost (localhost.localdomain [127.0.0.1]) by gate.crashing.org (8.14.1/8.14.1) with ESMTP id x5D234NX020590; Wed, 12 Jun 2019 21:03:05 -0500 Message-ID: <3093d174ddd183fe5b6e949a62a15e72aa373e26.camel@kernel.crashing.org> Subject: Re: [PATCH+DISCUSSION] irqchip: armada-370-xp: Remove redundant ops assignment From: Benjamin Herrenschmidt To: Thomas Petazzoni Cc: Gregory CLEMENT , Marc Zyngier , linux-arm-kernel@lists.infradead.org, "linux-kernel@vger.kernel.org" Date: Thu, 13 Jun 2019 12:03:04 +1000 In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2019-06-12 at 15:16 +1000, Benjamin Herrenschmidt wrote: > pci_msi_create_irq_domain -> pci_msi_domain_update_chip_ops will > set those two already since the driver sets MSI_FLAG_USE_DEF_CHIP_OPS > > Signed-off-by: Benjamin Herrenschmidt > --- > > [UNTESTED] > > Just something I noticed while browsing through those drivers in > search of ways to factor some of the code. > > That leads to a question here: > > Some MSI drivers such as this one (or any using the defaults > mask/unmask > provided by drivers/pci/msi.c) only call the PCI MSI mask/unmask > functions. > > Some other drivers call those PCI function but *also* call the parent > mask/unmask (giv-v2m for example) which generally is the inner domain > which just itself forwards to its own parent. .../... So I looked at x86 and it also only uses pci_msi_unmask_irq, it doesn't mask at the parent level. And it also specifies those explicitly which isn't necessary so the same trivial cleanup patch could be done (happy to do it unless I missed something here). Question: If that's indeed the rule we want to establish, should we consider making all MSI controllers just use the PCI masking and remove the forwarding to the parent ? The ones that do the parent, at least in drivers/irqchip/* and drivers/pci/controller/* (ther are more in arch code) are all the GIC ones (v2m, v3-its, v3-mbi), alpine which was copied on GIC I think, tango and dwc. The other approach would be to make the generic ops setup by pci_msi_domain_update_chip_ops call the parent as well .. if there is one and it has corresponding mask/unmask callbacks. That means things like armada_370 would be unaffected since their "middle" irqdomain chip doesn't have them, at least until somebody decides that masking at the parent level as well is a good thing. I *think* it would also work for x86 since the parent in that case is x86_vector_domain which also doesn't have mask and unmask callbacks, so it would be a nop change. Let me know what you think. Cheers, Ben.