Am 2020-04-30 22:19, schrieb Florian Fainelli:
On 4/30/20 1:13 PM, Michael Walle wrote:
Am 2020-04-30 22:04, schrieb Florian Fainelli:
On 4/30/20 12:41 PM, Andrew Lunn wrote:
ECD. The registers looks exactly like the one from the Marvell
PHYs,
which makes me wonder if both have the same building block or if
one
imitated the registers of the other. There are subtle differences
like one bit in the broadcom PHY is "break link" and is
self-clearing,
while the bit on the Marvell PHY is described as "perform
diagnostics
on link break".
Should we be sharing code between the two drivers?
Yes, I am amazed how how identical they are, nearly on a bit level
identical, the coincidence is uncanny. The expansion registers are
also
0x10 - 0x15 just in the reverse order,
At what PHY are you looking? I've just found some datasheets where
they
are at 0xC0 to 0xC5.
BCM54810 because that's what I have on my desk right now, but 0x10
would
be the offset relative to the expansion register space, which would
translate into this:
https://github.com/ffainelli/linux/commits/broadcom-cable-tests
(sorry for the mess it is a patchwork of tests on various platforms,
based on an earlier branch from Andrew).
Ah thanks, now I see what you mean with CD vs ECD. In your latest WIP
you're using ECD, so did both actually work with a link?
Also according to you header files bit 14 of the ECD_CTRL is the
"run after aneg bit"; in the BCM54140 it is just marked as reserved.
I guess I'm trying the CD on the BCM54140 tomorrow.
-michael
you know, so as to make it not
too obvious this looks about the same ;) I wonder if we managed to
find
something here.
What do you mean by calibrate it?
Some of the Marvell documentation talks about calibrating for losses
on the PCB. Run a diagnostics with no cable plugged in, and get the
cable length to the 'fault'. This gives you the distance to the RJ45
socket. You should then subtract that from all subsequent results.
But since this is board design specific, i decided to ignore it. I
suppose it could be stuffed into a DT property, but i got the
feeling
it is not worth it, given the measurement granularity of 80cm.
OK, accuracy is different here, they are said to be +/- 5m accurate
for
cable faults and +/- 10m accurate for good cables.
Accuracy != granularity. But yes, if one digit correspond to 80cm it
doesn't really make sense to remove the PCB trace error if you assume
that it might add just one digit at most.
One of the test racks that I use has very short cables, but I guess it
does not matter if they get reported as 80cm or 160cm...
