[PATCH 5.10 2/2] commit 1b5d73fb8624 ("igc: Enable PCIe PTM")

[Meng Tang <tangmeng@uniontech.com>]

In the 5.10 kernel version, even to the latest confirmed version,
the following error will still be reported when I225-V network card
is used.

kernel: [    1.031581] igc: probe of 0000:01:00.0 failed with error -2
kernel: [    1.066574] igc: probe of 0000:02:00.0 failed with error -2
kernel: [    1.096152] igc: probe of 0000:03:00.0 failed with error -2
kernel: [    1.127251] igc: probe of 0000:04:00.0 failed with error -2

Even though I confirmed that 7c496de538eebd8212dc2a3c9a468386b2640d4
and 47bca7de6a4fb8dcb564c7ca4d885c91ed19e03 have been merged into the
kernel 5.10, but bug still occurred, and this patch can fixes it.

Enables PCIe PTM (Precision Time Measurement) support in the igc
driver. Notifies the PCI devices that PCIe PTM should be enabled.

PCIe PTM is similar protocol to PTP (Precision Time Protocol) running
in the PCIe fabric, it allows devices to report time measurements from
their internal clocks and the correlation with the PCIe root clock.

The i225 NIC exposes some registers that expose those time
measurements, those registers will be used, in later patches, to
implement the PTP_SYS_OFFSET_PRECISE ioctl().

Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Tested-by: Dvora Fuxbrumer <dvorax.fuxbrumer@linux.intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: Meng Tang <tangmeng@uniontech.com>
---
 drivers/net/ethernet/intel/igc/igc_main.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index fd9257c7059a..298e968629db 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -10,6 +10,7 @@
 #include <linux/ip.h>
 #include <linux/pm_runtime.h>
 #include <net/pkt_sched.h>
+#include <linux/pci.h>
 
 #include <net/ipv6.h>
 
@@ -5041,6 +5042,10 @@ static int igc_probe(struct pci_dev *pdev,
 
 	pci_enable_pcie_error_reporting(pdev);
 
+	err = pci_enable_ptm(pdev, NULL);
+	if (err < 0)
+		dev_info(&pdev->dev, "PCIe PTM not supported by PCIe bus/controller\n");
+
 	pci_set_master(pdev);
 
 	err = -ENOMEM;
-- 
2.20.1