Hi Gert,
are you sure it sounds like a SATA link problem? It works fine
when the buffer is shorter (i.e. read 128 kilobytes then write
them, this in a loop taking about 10S, as expected).
Hey, I have to test with only a little longer buffer, 128k
is exactly 256 512 byte sectors (IRQ handles this differently
past that, may be this line is at fault... not much hope
as nothing would work if it were but I'll look into it
now :-) ).
Then making the cable better or worse did not affect things in the least....
There are no vias between the chip pads and the pads where the
cable is soldered to the board, the tx (the longer) traces are
about 20-25mm long, goint in parallel, meant to be 100 Ohm to each
other...
I wish I knew how to tell the part to go 1.5GbpS and not 3,
I can neither measure what it does there nor do I know how
to affect it (Marvell chip, no datasheet).
Dimiter
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From: "Havermann, Gert" <Gert.Havermann@xxxxxxxxxxx>
To: "dp@xxxxxxxxxxx" <dp@xxxxxxxxxxx>
Subject: AW: [SI-LIST] Longer SATA tx (host to drive) transfers issue
Date: Wed, 15 Jul 2015 09:27:35 +0000
Hi Dimiter,
sounds like a reflection problem. Check all via's in your design and
backrill every via stub that exeeds 1,3mm (when possible). You should
also TDR the Signal path if you have the equipment to do so.
BR
Gert
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Von: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] Im
Auftrag von Dimiter Popoff
Gesendet: Mittwoch, 15. Juli 2015 11:13
An: si-list@xxxxxxxxxxxxx
Betreff: [SI-LIST] Longer SATA tx (host to drive) transfers issue
Hi everyone,
I have a new version of a board of ours on which I
have put Marvells 88sa8052 ATA <-> SATA bridge.
I have tried it out using an off the shelf ATA <-> sata convertor and
it works fine. In fact I had soldered the convertor ATA side to the
former board version exactly as I (believe to) have routed
the chip on the board; and I put pulups/downs exactly as I saw
them on the convertor (unless I have made a mistake yet to be
discovered but I have checked a number of times already).
The chip I am using is taken from such a convertor (tested to work)
and... sort of works on my board. It does fine as long as I do not try
to write to the disk a longer buffer (100 megabytes copy via a 128k buffer
works just fine; give copy (I can do that easily, it is under
my control) a 4M buffer and I get lots of retries, takes forever
(about a minute vs. about 10S)...
I have checked the usual suspects - powers are stable and clean (during
the test, too), clock oscillator seems to run smoothly, the handshake signals
to the ATA side are OK.
The SATA cable is about 3 cm long, two pairs wound in copper foil,
properly connecting foil etc. to gnd points - and it seems to
work OK, no difference to 2 other - may be 2-3 times longer - cables
(ATA ribbon) I tried. Then it is just the longer write which causes the
problem.
I realize this is a long shot but someone on the list might have had to deal
with this or something similar and something might click.
Thanks,
Dimiter
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Dimiter Popoff Transgalactic Instruments
http://www.tgi-sci.com
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