Commit cc4a08cd authored by Bjorn Helgaas's avatar Bjorn Helgaas Committed by Lorenzo Pieralisi
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PCI: xgene: Fix CRS SV comment 

Configuration Request Retry Status ("CRS") must be supported by all PCIe
devices.  CRS Software Visibility is an optional feature that enables a
Root Port to make CRS visible to software by returning a special data value
to complete a config read.

Clarify a comment to say that it is "CRS SV", not "CRS", that can be
enabled.

Link: https://lore.kernel.org/r/20210126213503.2922848-1-helgaas@kernel.org


Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
Signed-off-by: default avatarLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
parent 5ce6697a

drivers/pci/controller/pci-xgene.c

+7 −6
Original line number Diff line number Diff line
@@ -173,12 +173,13 @@ static int xgene_pcie_config_read32(struct pci_bus *bus, unsigned int devfn, 


	/*

	 * The v1 controller has a bug in its Configuration Request

	 * Retry Status (CRS) logic: when CRS is enabled and we read the

	 * Vendor and Device ID of a non-existent device, the controller

	 * fabricates return data of 0xFFFF0001 ("device exists but is not

	 * ready") instead of 0xFFFFFFFF ("device does not exist").  This

	 * causes the PCI core to retry the read until it times out.

	 * Avoid this by not claiming to support CRS.

	 * Retry Status (CRS) logic: when CRS Software Visibility is

	 * enabled and we read the Vendor and Device ID of a non-existent

	 * device, the controller fabricates return data of 0xFFFF0001

	 * ("device exists but is not ready") instead of 0xFFFFFFFF

	 * ("device does not exist").  This causes the PCI core to retry

	 * the read until it times out.  Avoid this by not claiming to

	 * support CRS SV.

	 */

	if (pci_is_root_bus(bus) && (port->version == XGENE_PCIE_IP_VER_1) &&

	    ((where & ~0x3) == XGENE_V1_PCI_EXP_CAP + PCI_EXP_RTCTL))