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=-16.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 9A348C4338F for ; Tue, 24 Aug 2021 00:37:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7E67561284 for ; Tue, 24 Aug 2021 00:37:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233260AbhHXAig (ORCPT ); Mon, 23 Aug 2021 20:38:36 -0400 Received: from mail.kernel.org ([198.145.29.99]:44958 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233360AbhHXAig (ORCPT ); Mon, 23 Aug 2021 20:38:36 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 12364611F0; Tue, 24 Aug 2021 00:37:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1629765473; bh=c8B0rBovsBLEBI0TuOmV/QZyzMIZicWoE31njEO6kd4=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=pslhJVHYFMPYh1rSaZfq0i7PZg08+RU+E9f7DEv7zXgrc9TpUsjJTvWcSoJXczLRA cVuNf5uH9t58AxoUoi+SG/2CMe6B+FqqFwPVzSTZ2Zkwh7sHLoAmyffEdP2FFbrb/f Gb4I/UsOwT6LjjwBPM2jD1pqpWPDOlfB+xFz6+IU27rRazYXBgGjpB60ZDT+XZqmkV RXoQtEcmh9tyexYDj8qy6GUA5tos1hgcYTl1Z8UsyLPtf8InbZrhOpakVIrtAM/lRp t58GX2MecK0zHcSvmM7nEBTOgQlK7ayLFGtlVMujBXX1rEVu+m4tdxhHp5Z9JQ4eP1 vjnxnE/KEOy3g== Date: Mon, 23 Aug 2021 19:37:51 -0500 From: Bjorn Helgaas To: Jon Derrick Cc: linux-pci@vger.kernel.org, Ashok Raj , Lukas Wunner , jonathan.derrick@linux.dev, James Puthukattukaran Subject: Re: [PATCH v2] PCI: pciehp: Quirk to ignore spurious DLLSC when off Message-ID: <20210824003751.GA3417333@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210823184919.3412-1-jonathan.derrick@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Subject should start with a verb (see history for examples). "when off"? Needs a little more context to make sense by itself. On Mon, Aug 23, 2021 at 12:49:19PM -0600, Jon Derrick wrote: > From: James Puthukattukaran > > When a specific x8 CEM card is bifurcated into x4x4 mode, and the > upstream ports both support hotplugging on each respective x4 device, a > slot management system for the CEM card requires both x4 devices to be > sysfs removed from the OS before it can safely turn-off physical power. > The implications are that Slot Control will display Powered Off status > for the device where the device is actually powered until both ports > have powered off. Apparently this is related to a "specific x8 CEM card"? Please identify it (marketing name, model, etc -- some way a user can tell whether this quirk applies to the hardware he/she is holding), describe it, and make a case for why we care about it. E.g., if this is a shipping product, we probably do care; if it's just a lab fixture, maybe not. > When power is removed from the first half, real power and link remains > active while waiting for the second half to have power removed. When > power is then removed from the second half, the first half starts > shutdown sequence and will trigger a DLLSC event. This is misinterpreted > as an enabling event and causes the first half to be re-enabled. > > The spurious enable can be resolved by ignoring link status change > events when no link is active when in the off state. This patch adds a > quirk for the card. > > Acked-by: Jon Derrick > Signed-off-by: James Puthukattukaran > --- > v1->v2: Device-specific quirk > > drivers/pci/hotplug/pciehp_ctrl.c | 7 +++++++ > drivers/pci/quirks.c | 30 ++++++++++++++++++++++++++++++ > include/linux/pci.h | 1 + > 3 files changed, 38 insertions(+) > > diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c > index 529c34808440..db41f78bfac8 100644 > --- a/drivers/pci/hotplug/pciehp_ctrl.c > +++ b/drivers/pci/hotplug/pciehp_ctrl.c > @@ -225,6 +225,7 @@ void pciehp_handle_disable_request(struct controller *ctrl) > void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events) > { > int present, link_active; > + struct pci_dev *pdev = ctrl->pcie->port; > > /* > * If the slot is on and presence or link has changed, turn it off. > @@ -265,6 +266,12 @@ void pciehp_handle_presence_or_link_change(struct controller *ctrl, u32 events) > cancel_delayed_work(&ctrl->button_work); > fallthrough; > case OFF_STATE: > + if (pdev->shared_pcc_and_link_slot && > + (events & PCI_EXP_SLTSTA_DLLSC) && !link_active) { > + mutex_unlock(&ctrl->state_lock); > + break; > + } > + > ctrl->state = POWERON_STATE; > mutex_unlock(&ctrl->state_lock); > if (present) > diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c > index 43fbf55871ef..92a5bae8926e 100644 > --- a/drivers/pci/quirks.c > +++ b/drivers/pci/quirks.c > @@ -5749,3 +5749,33 @@ static void apex_pci_fixup_class(struct pci_dev *pdev) > } > DECLARE_PCI_FIXUP_CLASS_HEADER(0x1ac1, 0x089a, > PCI_CLASS_NOT_DEFINED, 8, apex_pci_fixup_class); > + > +/* > + * This is a special card that sits in a x8 pciehp slot but is bifurcated as > + * a x4x4 and manifests as two slots with respect to PCIe hot plug register > + * states. However, the hotplug controller treats these slots as a single x8 > + * slot for link and power. Either one of the two slots can be powered down > + * separately but real power and link will be active till the last of the two > + * slots is powered down. When the last of the two x4 slots is turned off, > + * power and link will be turned off for the x8 slot by the HP controller. > + * This configuration causes some interesting behavior in bringup sequence > + * > + * When the second slot is powered off to remove the card, this will cause > + * the link to go down for both x4 slots. So, the x4 that is already powered > + * down earlier will see a DLLSC event and attempt to bring itself up (card > + * present, link change event, link state is down). Special handling is > + * required in pciehp_handle_presence_or_link_change to prevent this unintended > + * bring up > + * > + */ > +static void shared_pcc_and_link_slot(struct pci_dev *pdev) > +{ > + struct pci_dev *parent = pci_upstream_bridge(pdev); > + > + if (pdev->subsystem_vendor == 0x108e && > + pdev->subsystem_device == 0x487d) { > + if (parent) > + parent->shared_pcc_and_link_slot = 1; > + } > +} > +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL, 0x0B60, shared_pcc_and_link_slot); > diff --git a/include/linux/pci.h b/include/linux/pci.h > index e752cc39a1fe..ba84f7c93c31 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -469,6 +469,7 @@ struct pci_dev { > > #ifdef CONFIG_HOTPLUG_PCI_PCIE > unsigned int broken_cmd_compl:1; /* No compl for some cmds */ > + unsigned int shared_pcc_and_link_slot:1; > #endif > #ifdef CONFIG_PCIE_PTM > unsigned int ptm_root:1; > -- > 2.27.0 >