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ice: Remove the E822 vernier "bypass" logic

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The E822 devices support an extended "vernier" calibration which enables
higher precision timestamps by accounting for delays in the PHY, and
compensating for them. These delays are measured by hardware as part of its
vernier calibration logic.

The driver currently starts the PHY in "bypass" mode which skips
the compensation. Then it later attempts to switch from bypass to vernier.
This unfortunately does not work as expected. Instead of properly
compensating for the delays, the hardware continues operating in bypass
without the improved precision expected.

Because we cannot dynamically switch between bypass and vernier mode,
refactor the driver to always operate in vernier mode. This has a slight
downside: Tx timestamp and Rx timestamp requests that occur as the very
first packet set after link up will not complete properly and may be
reported to applications as missing timestamps.

This occurs frequently in test environments where traffic is light or
targeted specifically at testing PTP. However, in practice most
environments will have transmitted or received some data over the network
before such initial requests are made.

Signed-off-by: Milena Olech <milena.olech@intel.com>
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>
This commit is contained in:
Milena Olech 2022-12-05 11:52:40 -08:00 • committed by Tony Nguyen
commit 0357d5cab8
3 changed files with 14 additions and 145 deletions
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