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PCI: xgene: Fix CRS SV comment

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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: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
This commit is contained in:
Bjorn Helgaas
2021-01-26 15:35:03 -06:00
committed by Lorenzo Pieralisi
parent 5ce6697a44
commit cc4a08cd09
1 changed files with 7 additions and 6 deletions
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13
drivers/pci/controller/pci-xgene.c
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@@ -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 * The v1 controller has a bug in its Configuration Request
* Retry Status (CRS) logic: when CRS is enabled and we read the * Retry Status (CRS) logic: when CRS Software Visibility is
* Vendor and Device ID of a non-existent device, the controller * enabled and we read the Vendor and Device ID of a non-existent
* fabricates return data of 0xFFFF0001 ("device exists but is not * device, the controller fabricates return data of 0xFFFF0001
* ready") instead of 0xFFFFFFFF ("device does not exist"). This * ("device exists but is not ready") instead of 0xFFFFFFFF
* causes the PCI core to retry the read until it times out. * ("device does not exist"). This causes the PCI core to retry
* Avoid this by not claiming to support CRS. * 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) && if (pci_is_root_bus(bus) && (port->version == XGENE_PCIE_IP_VER_1) &&
((where & ~0x3) == XGENE_V1_PCI_EXP_CAP + PCI_EXP_RTCTL)) ((where & ~0x3) == XGENE_V1_PCI_EXP_CAP + PCI_EXP_RTCTL))