"Duyck, Alexander H" <[email protected]> wrote:
> The problem is that there is only one register.  As a result when you
> read the E1000_RXSTMP[LH] you end up reading the last timestamp that
> was recorded, not necessarily the one for your packet.  This is due to
> the fact that all locking of the registers is disabled when set to
> 100b.

But, AFAIR, in my tests the timestamp registers were not updated for
anything other than ptp packets.  Reading E1000_RXSTMP[LH] when
.._STAT_TS was not set resulted in some constant (I think it was zero).
I can check it once more if necessary.

> The next version of the hardware, the 82580 MAC, will have support for
> placing the timestamps into the packet header itself so then when you

Thanks for the info.  Just had a look at it; 82580 support seems to be
added just a few days ago to the mainline kernel.

> enable the timestamp all mode you will be able to differentiate the
> timestamps between packets.

Then I think igb_hwtstamp_ioctl() can be changed to return -ERANGE for
models not supporting them.

Thanks,
Ali

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