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? The following are changes since commit 3a62c333497b164868fdcd241842a1dd4e331825: Merge branch 'ethtool-extend-coalesce-uapi' and are available in the git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/tnguy/next-queue 1GbE Vinicius Costa Gomes (4): Revert "PCI: Make pci_enable_ptm() private" PCI: Add pcie_ptm_enabled() igc: Enable PCIe PTM igc: Add support for PTP getcrosststamp() drivers/net/ethernet/intel/igc/igc.h | 1 + drivers/net/ethernet/intel/igc/igc_defines.h | 31 ++++ drivers/net/ethernet/intel/igc/igc_main.c | 6 + drivers/net/ethernet/intel/igc/igc_ptp.c | 179 +++++++++++++++++++ drivers/net/ethernet/intel/igc/igc_regs.h | 23 +++ drivers/pci/pci.h | 3 - drivers/pci/pcie/ptm.c | 9 + include/linux/pci.h | 10 ++ 8 files changed, 259 insertions(+), 3 deletions(-) -- 2.26.2
