PCI: Enable SERR# forwarding for all bridges (b4f6dcb9) · Commits · 戴 / test

As per Figure 6-3 in PCIe r4.0, sec 6.2.6, ERR_ messages will be forwarded from the secondary interface to the primary interface, if the SERR# Enable bit in the Bridge Control register is set. It seems clear that an ACPI hotplug parameter method (_HPP or _HPX) that tells us to "enable SERR in the command register" (ACPI v6.2, sec 6.2.8, 6.2.9.1) refers to PCI_COMMAND_SERR, which enables reporting of errors by the function itself. For bridges, we also interpreted that to mean we should enable PCI_BRIDGE_CTL_SERR, which enables *forwarding* of errors by the bridge. But we didn't enable PCI_BRIDGE_CTL_SERR anywhere else, which means we never enabled it for non-ACPI systems or ACPI systems that didn't supply hotplug parameters. That means errors reported below bridges were often never forwarded up to a Root Port where they could be signaled via AER. Enable PCI_BRIDGE_CTL_SERR for all bridges so we can get better error reporting for downstream devices. Signed-off-by:

Bharat Kumar Gogada <bharat.kumar.gogada@xilinx.com> [bhelgaas: changelog] Signed-off-by:

Bjorn Helgaas <bhelgaas@google.com>

drivers/pci/probe.c

+19 −2

Original line number	Diff line number	Diff line
		@@ -1856,8 +1856,6 @@ static void program_hpp_type0(struct pci_dev dev, struct hpp_type0 hpp)
		pci_write_config_byte(dev, PCI_SEC_LATENCY_TIMER,
		hpp->latency_timer);
		pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &pci_bctl);
		if (hpp->enable_serr)
		pci_bctl \|= PCI_BRIDGE_CTL_SERR;
		if (hpp->enable_perr)
		pci_bctl \|= PCI_BRIDGE_CTL_PARITY;
		pci_write_config_word(dev, PCI_BRIDGE_CONTROL, pci_bctl);
		@@ -2129,6 +2127,24 @@ static void pci_configure_eetlp_prefix(struct pci_dev *dev)
		#endif
		}

		static void pci_configure_serr(struct pci_dev *dev)
		{
		u16 control;

		if (dev->hdr_type == PCI_HEADER_TYPE_BRIDGE) {

		/*
		* A bridge will not forward ERR_ messages coming from an
		* endpoint unless SERR# forwarding is enabled.
		*/
		pci_read_config_word(dev, PCI_BRIDGE_CONTROL, &control);
		if (!(control & PCI_BRIDGE_CTL_SERR)) {
		control \|= PCI_BRIDGE_CTL_SERR;
		pci_write_config_word(dev, PCI_BRIDGE_CONTROL, control);
		}
		}
		}

		static void pci_configure_device(struct pci_dev *dev)
		{
		struct hotplug_params hpp;
		@@ -2139,6 +2155,7 @@ static void pci_configure_device(struct pci_dev *dev)
		pci_configure_relaxed_ordering(dev);
		pci_configure_ltr(dev);
		pci_configure_eetlp_prefix(dev);
		pci_configure_serr(dev);

		memset(&hpp, 0, sizeof(hpp));
		ret = pci_get_hp_params(dev, &hpp);

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