Hi, I've been working on implementing support for PTP in the E810 and E822 devices for Intel's ice driver. As part of this work we've discovered that (again...) timestamps can sometimes take longer than the 1millisecond default delay.
Although we get an interrupt within 10usec, the timestamp has to be retrieved from a PHY register, and this access is unfortunately mediated by firmware. The result is that while we can sometimes recover the timestamp within the 1000usec default delay, we sometimes need as much as 2000 or 2500 usec. We've been recommending that people default to using tx_timestamp_timeout of 5 or 10 to avoid issues. I am wondering if there would be support for either (a) increasing the default timeout, or (b) adding something to the PTP get capabilities for indicating a sort of default timeout for the device, and if it's not set in the config then the default timeout is used? The reason for this need is because it is confusing for users to be immediately prompted with "this is likely a driver bug" messaging. We know that the only resolution is to wait slightly longer. This is also not the first time we've had issues with the 1msec delay being too short, I believe we've often had to recommend increasing the delay for other Intel parts in the past for similar reasons. Note I tried a number of changes to the driver implementation in order to see if I could reduce the delay, and although I was able to improve it, I was never able to get it consistently below 1000usec, as we're effectively limited by the need to read the register access over the firmware :( Thanks, Jake
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