Re: [LAD] Writing an IEEE 802.1BA (AVB) compliant network backend for Jack2 - Linux-audio-dev

5 Apr 2011

On Tue, Apr 05, 2011 at 08:29:03AM -0700, Stephen Hemminger wrote:

Just a full quote for the list, I guess Stephen's mail hasn't reached
anyone but me due to subscribers-only policy on LAD.

...
   On 04/05/11
11:53, Christoph Kuhr wrote:

 Hi!

  apparently the ASUS 890FX mainboard has a yukon
88e8059 nic, which i
 have not verified yet.  
 To be precise, it's only the Crosshair IV Formular 890FX, all others
 either have Realtek or Intel.

  the marvell yukon 88e8059 specs say this nic is
avb ready.  
 Indeed, at least if we believe the little PDF provided by Marvell.

 I don't know exactly what this means, it seems they support multiple
 RX/TX queues, so AVB packages might end up in a priority lane while bulk
 traffic is handled via a different queue.  
 It has 2 Tx queues, but one is not used because it really doesn't
 offer any benefit. The sync Tx queue doesn't fit the Linux
 multiple Tx queue model.

  They also support hardware timestamping. The
Linux driver in question is
 sky2, in sky2.h, they already have some PTP related defines, but the
 sky2.c doesn't make use of them.  
 The hardware timestamping is also disabled in Linux for a couple
 of reasons. First the wraparound of the timestamp is not well
 documented, but more importantly timestamping and RSS hash can
 not be combined and RSS hash seemed more useful. 
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