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10e4b4a3a3
The PHY for E822 based hardware has a register which indicates which timestamps are valid in the PHY timestamp memory block. Each bit in the register indicates whether the associated index in the timestamp memory is valid. Hardware sets this bit when the timestamp is captured, and clears the bit when the timestamp is read. Use of this register is important as reading timestamp registers can impact the way that hardware generates timestamp interrupts. This occurs because the PHY has an internal value which is incremented when hardware captures a timestamp and decremented when software reads a timestamp. Reading timestamps which are not marked as valid still decrement the internal value and can result in the Tx timestamp interrupt not triggering in the future. To prevent this, use the timestamp memory value to determine which timestamps are ready to be read. The ice_get_phy_tx_tstamp_ready function reads this value. For E810 devices, this just always returns with all bits set. Skip any timestamp which is not set in this bitmap, avoiding reading extra timestamps on E822 devices. The stale check against a cached timestamp value is no longer necessary for PHYs which support the timestamp ready bitmap properly. E810 devices still need this. Introduce a new verify_cached flag to the ice_ptp_tx structure. Use this to determine if we need to perform the verification against the cached timestamp value. Set this to 1 for the E810 Tx tracker init function. Notice that many of the fields in ice_ptp_tx are simple 1 bit flags. Save some structure space by using bitfields of length 1 for these values. Modify the ICE_PTP_TS_VALID check to simply drop the timestamp immediately so that in an event of getting such an invalid timestamp the driver does not attempt to re-read the timestamp again in a future poll of the register. With these changes, the driver now reads each timestamp register exactly once, and does not attempt any re-reads. This ensures the interrupt tracking logic in the PHY will not get stuck. Signed-off-by: Jacob Keller <jacob.e.keller@intel.com> Tested-by: Gurucharan G <gurucharanx.g@intel.com> (A Contingent worker at Intel) Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com> |
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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.