From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753699AbeBLSzM (ORCPT ); Mon, 12 Feb 2018 13:55:12 -0500 Received: from bmailout3.hostsharing.net ([176.9.242.62]:45805 "EHLO bmailout3.hostsharing.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751196AbeBLSzK (ORCPT ); Mon, 12 Feb 2018 13:55:10 -0500 Date: Mon, 12 Feb 2018 19:55:08 +0100 From: Lukas Wunner To: Bjorn Helgaas Cc: linux-pci@vger.kernel.org, Prarit Bhargava , linux-kernel@vger.kernel.org, MUNEDA Takahiro , Kenji Kaneshige Subject: Re: [PATCH] PCI/portdrv: Remove "pcie_hp=nomsi" kernel parameter Message-ID: <20180212185508.GB3862@wunner.de> References: <20180211024815.73781.92853.stgit@bhelgaas-glaptop.roam.corp.google.com> <20180211092525.GA1085@wunner.de> <20180212150146.GA75542@bhelgaas-glaptop.roam.corp.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180212150146.GA75542@bhelgaas-glaptop.roam.corp.google.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 12, 2018 at 09:01:46AM -0600, Bjorn Helgaas wrote: > On Sun, Feb 11, 2018 at 10:25:25AM +0100, Lukas Wunner wrote: > > On Sat, Feb 10, 2018 at 08:48:15PM -0600, Bjorn Helgaas wrote: > > > 7570a333d8b0 ("PCI: Add pcie_hp=nomsi to disable MSI/MSI-X for pciehp > > > driver") added the "pcie_hp=nomsi" kernel parameter to work around this > > > error on shutdown: > > > > > > irq 16: nobody cared (try booting with the "irqpoll" option) > > > Pid: 1081, comm: reboot Not tainted 3.2.0 #1 > > > ... > > > Disabling IRQ #16 > > > > > > This happened on an unspecified system (possibly involving the Integrated > > > Device Technology, Inc. Device 807f bridge). There is no automated way to > > > set this parameter, so it's not very useful for distributions or end users. > > > > > > I suspect the root cause of the underlying "irq 16: nobody cared" issue was > > > fixed by Prarit Bhargava with fda78d7a0ead ("PCI/MSI: > > > Stop disabling MSI/MSI-X in pci_device_shutdown()") and we probably don't > > > need "pcie_hp=nomsi" any more. > > > > > > Revert 7570a333d8b0 to remove the "pcie_hp=nomsi" parameter. > > > > This has been useful when bringing up broken hardware which claims to > > support MSI but really doesn't, such as in commit 19bf4d4f909d > > ("thunderbolt: Support 1st gen Light Ridge controller"). In this case > > I didn't know why the controller wasn't sending interrupts, on a hunch > > I tried "pcie_hp=nomsi" and that worked, and looking in the macOS source > > code I was able to verify that they disable MSI for this particular > > hardware as well. So please leave it in to ease developers' lives. > > Wouldn't "pci=nomsi" be sufficient for that sort of bringup > experimentation? We don't need to be super specific in that > situation. I'm not sure if that would work as it also disables MSI for anything not a hotplug bridge. > The reason I want to remove it is that the port driver > (drivers/pci/pcie/portdrv*) has become a rat's nest of switches and > special cases, and I'm trying to simplify it. Things like > "pcie_hp=nomsi" are trivial individually, but collectively it's > getting unmanageable. I see your point and don't want to stand in the way of progress. It just was a useful tool for me once, that's all I'm saying, I probably won't need it again, but maybe someone else will. Thanks, Lukas