Dear Vinicius,
Am 08.06.21 um 21:02 schrieb Vinicius Costa Gomes:
Paul Menzel writes:
Am 05.06.21 um 02:23 schrieb Vinicius Costa Gomes:
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@xxxxxxxxx>
---
drivers/net/ethernet/intel/igc/igc_main.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index a05e6d8ec660..f23d0303e53b 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -12,6 +12,8 @@
#include <net/pkt_sched.h>
#include <linux/bpf_trace.h>
#include <net/xdp_sock_drv.h>
+#include <linux/pci.h>
+
#include <net/ipv6.h>
#include "igc.h"
@@ -5864,6 +5866,10 @@ static int igc_probe(struct pci_dev *pdev,
pci_enable_pcie_error_reporting(pdev);
+ err = pci_enable_ptm(pdev, NULL);
+ if (err < 0)
+ dev_err(&pdev->dev, "PTM not supported\n");
+
Sorry, if I am missing something, but do all devices supported by this
driver support PTM or only the i225 NIC? In that case, it wouldn’t be an
error for a device not supporting PTM, would it?
That was a very good question. I had to talk with the hardware folks.
All the devices supported by the igc driver should support PTM.
Thank you for checking that, that is valuable information.
And just to be clear, the reason that I am not returning an error here
is that PTM could not be supported by the host system (think PCI
controller).
I just checked `pci_enable_ptm()` and on success it calls
`pci_ptm_info()` logging a message:
pci_info(dev, "PTM enabled%s, %s granularity\n",
dev->ptm_root ? " (root)" : "", clock_desc);
Was that present on your system with your patch? Please add that to the
commit message.
Regarding my comment, I did not mean returning an error but the log
*level* of the message. So, `dmesg --level err` would show that message.
But if there are PCI controllers not supporting that, it’s not an error,
but a warning at most. So, I’d use:
dev_warn(&pdev->dev, "PTM not supported by PCI bus/controller
(pci_enable_ptm() failed)\n");
pci_set_master(pdev);
err = -ENOMEM;
Kind regards,
Paul
