From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp.codeaurora.org ([198.145.29.96]:46140 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725913AbeGNHdm (ORCPT ); Sat, 14 Jul 2018 03:33:42 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Date: Sat, 14 Jul 2018 12:45:38 +0530 From: poza@codeaurora.org To: Bharat Kumar Gogada Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, bhelgaas@google.com, linux-pci-owner@vger.kernel.org Subject: Re: [PATCH] PCI/AER: Enable SERR# forwarding in non ACPI flow In-Reply-To: References: <1531406719-18606-1-git-send-email-bharat.kumar.gogada@xilinx.com> Message-ID: <3bd31b729f9f335fcd906a8164c0a4cb@codeaurora.org> Sender: linux-pci-owner@vger.kernel.org List-ID: On 2018-07-13 19:25, Bharat Kumar Gogada wrote: >> > Currently PCI_BRIDGE_CTL_SERR is being enabled only in ACPI flow. >> > This bit is required for forwarding errors reported by EP devices to >> > upstream device. >> > This patch enables SERR# for Type-1 PCI device. >> > >> > Signed-off-by: Bharat Kumar Gogada >> > --- >> > drivers/pci/pcie/aer.c | 23 +++++++++++++++++++++++ >> > 1 files changed, 23 insertions(+), 0 deletions(-) >> > >> > diff --git a/drivers/pci/pcie/aer.c b/drivers/pci/pcie/aer.c index >> > a2e8838..943e084 100644 >> > --- a/drivers/pci/pcie/aer.c >> > +++ b/drivers/pci/pcie/aer.c >> > @@ -343,6 +343,19 @@ int pci_enable_pcie_error_reporting(struct >> > pci_dev >> > *dev) >> > if (!dev->aer_cap) >> > return -EIO; >> > >> > + if (!IS_ENABLED(CONFIG_ACPI) && >> > + dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) { >> > + u16 control; >> > + >> > + /* >> > + * A Type-1 PCI bridge will not forward ERR_ messages >> coming >> > + * from an endpoint if SERR# forwarding is not enabled. >> > + */ >> > + pci_read_config_word(dev, PCI_BRIDGE_CONTROL, >> &control); >> > + control |= PCI_BRIDGE_CTL_SERR; >> > + pci_write_config_word(dev, PCI_BRIDGE_CONTROL, control); >> > + } >> > + >> > return pcie_capability_set_word(dev, PCI_EXP_DEVCTL, >> > PCI_EXP_AER_FLAGS); } >> > EXPORT_SYMBOL_GPL(pci_enable_pcie_error_reporting); >> > @@ -352,6 +365,16 @@ int pci_disable_pcie_error_reporting(struct >> > pci_dev *dev) >> > if (pcie_aer_get_firmware_first(dev)) >> > return -EIO; >> > >> > + if (!IS_ENABLED(CONFIG_ACPI) && >> > + dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) { >> > + u16 control; >> > + >> > + /* Clear SERR Forwarding */ >> > + pci_read_config_word(dev, PCI_BRIDGE_CONTROL, >> &control); >> > + control &= ~PCI_BRIDGE_CTL_SERR; >> > + pci_write_config_word(dev, PCI_BRIDGE_CONTROL, control); >> > + } >> > + >> > return pcie_capability_clear_word(dev, PCI_EXP_DEVCTL, >> > PCI_EXP_AER_FLAGS); >> > } >> >> >> Should this configuration no be set by Firmware ? why should Linux >> dictate it >> ? > Hi Oza, Can you please let us know why this should be set by firmware ? > Spec clearly states ERR_CORR,ERR_FATAL/NON FATAL will be forwarded > only if this bit is set. > If linux AER service is being enabled without checking/setting this > bit, then AER service will > not do anything even ERR_* is seen on link. > > Regards, > Bharat The ERR_* to be forwarded or not to be forwarded could be decision of the platform. hence I think it is best left to firmware to decide if it want to enable this for particular platform. although, There are 2 cases Hotplug capable bridge and otherwise. 1) If Firmware sets them, I do not think during enumeraion linux will loose those settings. 2) I do not see any integration of hotplug with AER currently, so if the PCIe switch is plugged into Hotplug capable RP, I am not very sure if this functions get called. Keith, Lukas and Bjorn any comments ? Regards, Oza.