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 32E26C54EBD for ; Fri, 13 Jan 2023 17:58:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229825AbjAMR6x (ORCPT ); Fri, 13 Jan 2023 12:58:53 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39668 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231138AbjAMR6f (ORCPT ); Fri, 13 Jan 2023 12:58:35 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9A91F7F9D7; Fri, 13 Jan 2023 09:51:39 -0800 (PST) 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 ED2D3622D0; Fri, 13 Jan 2023 17:51:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1E1C0C433D2; Fri, 13 Jan 2023 17:51:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1673632298; bh=3LnsMdjPcXTZVEHkBWK5abIQvnrNhWuNASnKmgc+Fgs=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=cipZBDKw064GTZrUKI/yNHcV+IPnDLtFInQKkG04Ax3FbPKeiZqrZm57AqWLKN5SG TrxYhMa50EX7bQGyspOBPhY0eHqZ4yfLOpuGLytRrPWPlPCjpazbWTAh45Z9pBA3l7 xu18lp3TMgnsUejX781ScR+woiUWTpvS8k9kzVgyqxMI9UdTzDkt6m2FqzF0ykcYCe 09K639BJ5Jmi/QEn0BJ+NLiln2FbLEkEvYT72bMEJHcWyDrIZYka5U60C+itgD5lzn 9jCLmip8J1cXtv36jstTU6rh9X67XvMrnWOZ3m2VvfOe3VigHrnTtJ0rZpQz+0Mp48 NVkLzTbc41Pyw== Date: Fri, 13 Jan 2023 11:51:36 -0600 From: Bjorn Helgaas To: "Limonciello, Mario" Cc: "Rafael J. Wysocki" , "linux-pci@vger.kernel.org" , "Rafael J. Wysocki" , Len Brown , Bjorn Helgaas , Mika Westerberg , "Mehta, Sanju" , Lukas Wunner , "Rafael J . Wysocki" , "linux-acpi@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Linux PM Subject: Re: [PATCH v4] PCI / ACPI: PM: Take _S0W of the target bridge into account in acpi_pci_bridge_d3(() Message-ID: <20230113175136.GA1848594@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Thu, Jan 12, 2023 at 10:45:03PM +0000, Limonciello, Mario wrote: > [AMD Official Use Only - General] > > > > > -----Original Message----- > > From: Bjorn Helgaas > > Sent: Thursday, January 12, 2023 16:41 > > To: Limonciello, Mario > > Cc: Rafael J. Wysocki ; linux-pci@vger.kernel.org; Rafael J. > > Wysocki ; Len Brown ; Bjorn Helgaas > > ; Mika Westerberg > > ; Mehta, Sanju ; > > Lukas Wunner ; Rafael J . Wysocki > > ; linux-acpi@vger.kernel.org; linux- > > kernel@vger.kernel.org; Linux PM > > Subject: Re: [PATCH v4] PCI / ACPI: PM: Take _S0W of the target bridge into > > account in acpi_pci_bridge_d3(() > > > > On Thu, Jan 12, 2023 at 10:09:21PM +0000, Limonciello, Mario wrote: > > > > -----Original Message----- > > > > From: Bjorn Helgaas > > > > Sent: Thursday, January 12, 2023 16:02 > > > > To: Rafael J. Wysocki > > > > Cc: linux-pci@vger.kernel.org; Limonciello, Mario > > > > ; Rafael J. Wysocki ; > > Len > > > > Brown ; Bjorn Helgaas ; Mika > > > > Westerberg ; Mehta, Sanju > > > > ; Lukas Wunner ; Rafael J . > > > > Wysocki ; linux-acpi@vger.kernel.org; linux- > > > > kernel@vger.kernel.org; Linux PM > > > > Subject: Re: [PATCH v4] PCI / ACPI: PM: Take _S0W of the target bridge into > > > > account in acpi_pci_bridge_d3(() > > > > > > > > On Thu, Jan 12, 2023 at 09:51:24PM +0100, Rafael J. Wysocki wrote: > > > > > From: Rafael J. Wysocki > > > > > > > > > > It is generally questionable to allow a PCI bridge to go into D3 if > > > > > it has _S0W returning D2 or a shallower power state, so modify > > > > > acpi_pci_bridge_d3(() to always take the return value of _S0W for the > > > > > target bridge into accout. That is, make it return 'false' if _S0W > > > > > returns D2 or a shallower power state for the target bridge regardless > > > > > of its ancestor PCIe Root Port properties. Of course, this also causes > > > > > 'false' to be returned if the PCIe Root Port itself is the target and > > > > > its _S0W returns D2 or a shallower power state. > > > > > > > > > > However, still allow bridges without _S0W that are power-manageable via > > > > > ACPI to enter D3 to retain the current code behavior in that case. > > > > > > > > > > Link: https://lore.kernel.org/linux-pci/20221031223356.32570-1- > > > > mario.limonciello@amd.com/ > > > > > Reported-by: Mario Limonciello > > > > > Signed-off-by: Rafael J. Wysocki > > > > > > > > Applied to pci/pm for v6.3, thanks! > > > > > > > > It'd be great if we could include a short description of the problems > > > > users might see. I think the original problem was that on some AMD > > > > systems we put a USB4 router in D3 when it should remain in D0. And I > > > > assume this means something doesn't wake up when it should? Or maybe > > > > we miss a hotplug event? > > > > > > > > If somebody has an example or some text, I'll add it to the commit > > > > log. > > > > > > Here's a blurb for what happens on AMD side: > > > > > > When the platform is configured to not allow the PCIe port used for > > > tunneling to wakeup from D3 it will runtime suspend into D0 and the > > > USB4 controller which is a consumer will runtime suspend into D3. > > > > > > This inconsistency leads to failures to initialize PCIe tunnels for > > > USB4 devices. > > > > And what is J. Random User going to see? DisplayPort not working > > ever? It works to begin with, but not after a suspend? Devices in a > > dock not being able to wake the system? > > > > I don't really know what "PCIe tunnels for USB4 devices not being > > initialized" means for me. I want to know what a problem report from > > a non-expert user might look like. > > DP tunnels aren't affected, so monitors should still work. > > In terms of what doesn't work it depends on the architecture of the > the connected device. Here's some concrete up-leveled examples: > > USB4 docks contain that a PCIe network adapter and that adapter won't > work when the dock is plugged in after the system boot. > > USB4 docks that contain a USB network adapter should work properly, > but downstream USB4 or TBT3 devices connected to that USB4 dock will > not work when the device or dock is plugged in after the system boots. > > TBT3 storage devices connected after the system has booted will not work. Thanks, this is exactly the sort of thing I was looking for. Since they all mention "connected after boot," I assume the issue with the current code is that a hotplug notification is being missed because a bridge is in D3. If the devices are present and enumerated at boot, there's no issue with suspend/resume, right? What do you think of the following possible text? I don't want to be overly specific because I don't think it's practical to list every scenario. We just need a hook to make people think "Hmm, I'm seeing a dock issue; maybe this is the fix." This fixes problems where a hotplug notification is missed because a bridge is in D3. That means hot-added devices such as USB4 docks (and the devices they contain) and Thunderbolt 3 devices may not work.