Merge branch '1GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/next-queue

Merge branch '1GbE' of git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/next-queue

Tony Nguyen says:

====================
1GbE Intel Wired LAN Driver Updates 2021-08-24

Vinicius Costa Gomes says:

This adds support for PCIe PTM (Precision Time Measurement) to the igc
driver. PCIe PTM allows the NIC and Host clocks to be compared more
precisely, improving the clock synchronization accuracy.

Patch 1/4 reverts a commit that made pci_enable_ptm() private to the
PCI subsystem, reverting makes it possible for it to be called from
the drivers.

Patch 2/4 adds the pcie_ptm_enabled() helper.

Patch 3/4 calls pci_enable_ptm() from the igc driver.

Patch 4/4 implements the PCIe PTM support. Exposing it via the
.getcrosststamp() API implies that the time measurements are made
synchronously with the ioctl(). The hardware was implemented so the
most convenient way to retrieve that information would be
asynchronously. So, to follow the expectations of the ioctl() we have
to use less convenient ways, triggering an PCIe PTM dialog every time
a ioctl() is received.

Some questions are raised (also pointed out in the commit message):

1. Using convert_art_ns_to_tsc() is too x86 specific, there should be
   a common way to create a 'system_counterval_t' from a timestamp.

2. convert_art_ns_to_tsc() says that it should only be used when
   X86_FEATURE_TSC_KNOWN_FREQ is true, but during tests it works even
   when it returns false. Should that check be done?
====================

Signed-off-by: David S. Miller <davem@davemloft.net>