mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
synced 2025-01-11 08:18:47 +00:00
d484dc2b21
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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.