[Intel-wired-lan] [PATCH next-queue v5 3/4] igc: Enable PCIe PTM
Vinicius Costa Gomes
vinicius.gomes at intel.com
Wed Jun 9 20:08:22 UTC 2021
Paul Menzel <pmenzel at molgen.mpg.de> writes:
> 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 at intel.com>
>>>> ---
>>>> 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.
Yes, with my patches applied I can see this message on my systems.
Sure, will add this 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");
I will use you suggestion for the message, but I think that warn is a
bit too much, info or notice seem to be better.
Cheers,
--
Vinicius
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