[MinnowBoard] MinnowBoard MAX 0.93 64-Bit & network lost

Wei, David david.wei at intel.com
Mon Sep 12 02:36:00 UTC 2016


For VO.92, the BIOS setup option "Spread Clock Spectrum" could only control the external clock generator, it cannot affect PCIe Spread Clock Spectrum. Because PCIe Spread Clock Spectrum is a feature controlled by "software strap", which is out of the scope of BIOS. 

But for V0.93, in order to pass FCC test, Spread Clock Spectrum of PCIe is required to be enabled (by changing the "software strap" bit that I shared before), and also the BIOS setup option "Spread Clock Spectrum" is required to be hidden from end user. 

David  Wei                                 

-----Original Message-----
From: elinux-MinnowBoard [mailto:elinux-minnowboard-bounces at lists.elinux.org] On Behalf Of David Scully
Sent: Saturday, September 10, 2016 3:45 AM
To: elinux-minnowboard at lists.elinux.org
Subject: Re: [MinnowBoard] MinnowBoard MAX 0.93 64-Bit & network lost

Thank you for this quick fix so I didn't have to rebuild the 0.93 firmware to
turn this off.

It appears that making this modification has resolved my issues with PCIe
disconnects. I'm still not sure why I didn't see problems with 0.92 with
Spread Clock Spectrum turned on -- Has something changed under the hood for
how that feature works between 0.92 and 0.93?

We're looking at doing some layout review and checking our our eye diagram.
This feature might have pushed our design into a marginal state.

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