diff mbox series

PCI: xgene: Fix CRS SV comment

Message ID 20210126213503.2922848-1-helgaas@kernel.org (mailing list archive)
State Accepted
Headers show
Series PCI: xgene: Fix CRS SV comment | expand

Commit Message

Bjorn Helgaas Jan. 26, 2021, 9:35 p.m. UTC 
From: Bjorn Helgaas <bhelgaas@google.com>

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.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/pci/controller/pci-xgene.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

Comments

Lorenzo Pieralisi Jan. 28, 2021, 10:47 a.m. UTC | #1 
On Tue, 26 Jan 2021 15:35:03 -0600, Bjorn Helgaas wrote:
> 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.

Applied to pci/misc, thanks!

[1/1] PCI: xgene: Fix CRS SV comment
      https://git.kernel.org/lpieralisi/pci/c/cc4a08cd09

Thanks,
Lorenzo
diff mbox series

Patch

diff --git a/drivers/pci/controller/pci-xgene.c b/drivers/pci/controller/pci-xgene.c
index 85e7c98265e8..2afdc865253e 100644
--- a/drivers/pci/controller/pci-xgene.c
+++ b/drivers/pci/controller/pci-xgene.c
@@ -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))