FWIW, this thread ends up in the spam folder for me also on my private
e-mail account. And it's not the only Broadcom thread. Quite a few
Broadcom e-mails end up there. The thread was sent to me via
infradead.org. My private e-mail is also hosted by Gmail.

I get this:

SPF: PASS with IP 2001:1868:205:0:0:0:0:9 Learn more
DKIM: NEUTRAL with domain null Learn more
DMARC: FAIL Learn more

So, it's not DKIM for me, but DMARC that's failing.

The actual headers:

Received: from bombadil.infradead.org (bombadil.infradead.org.
[2001:1868:205::9])
        by mx.google.com with ESMTPS id
r127si16944054pgr.251.2016.10.24.12.13.37
        for [off-list ref]
        (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
        Mon, 24 Oct 2016 12:13:37 -0700 (PDT)
Received-SPF: pass (google.com: best guess record for domain of
linux-arm-kernel-bounces+mmayer=mmayer.net at lists.infradead.org
designates 2001:1868:205::9 as permitted sender)
client-ip=2001:1868:205::9;
Authentication-Results: mx.google.com;
       dkim=neutral (body hash did not verify) header.i=@broadcom.com;
       spf=pass (google.com: best guess record for domain of
linux-arm-kernel-bounces+mmayer=mmayer.net at lists.infradead.org
designates 2001:1868:205::9 as permitted sender)
smtp.mailfrom=linux-arm-kernel-bounces+mmayer=mmayer.net at lists.infradead.org;
       dmarc=fail (p=QUARANTINE dis=NONE) header.from=broadcom.com
Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by
bombadil.infradead.org

Regards,
-Markus