Re: [Linuxptp-users] issue with NetXtreme II BCM57810

[Richard C. <ric...@gm...>]

On Tue, Oct 04, 2016 at 10:49:46AM +0000, Luke Bigum wrote:
> If I do some simple tests with linux/Documentation/ptp/testptp.c, it
> appears the PHC is spinning at about half the Hz it should be doing
> (it takes roughly 2 real seconds for the PHC to advance 1
> second). While it is an anecdotal observation, half as fast seems
> rather uniform a problem, like there's a /2 somewhere gone wrong in
> the driver code...  If I wanted to dig into the bnx2x source, any
> pointers on where to start looking?

I don't have this card nor was I involved in reviewing the driver.
The file, drivers/net/ethernet/broadcom/bnx2x/bnx2x_main.c, contains
the PHC stuff.

Looking at bnx2x_init_cyclecounter(), they have mult = shift = 1.
That implies that

  nanoseconds = ticks / 2

and that their internal clock runs at 2 GHz!

Maybe they meant to have shift=0, or maybe your card has a (model
specific 1 GHz clock).

Anyhow, the testptp result is clear enough.  You should take this up
with the driver maintainers.

Thanks,
Richard