gianfar.c: Unwanted VLAN tagging on TX frames

Torsten Fleischer to-fleischer at
Wed Aug 26 03:08:55 EST 2009

On Tuesday 25 August 2009 at 01:32:18, Andy Fleming wrote:

> have you tested this?  This looks like it has a bad race
> condition.  The TCTRL register applies to all packets, which means if you
> send a packet with VLAN tags, followed by one without, or visa versa,
> there's a reasonable chance that the second packet's VLAN tags (or lack
> thereof) will take precedence.
> Without speaking for the company, I suspect that this is just how the eTSEC
> works with VLAN -- all, or nothing.
> Andy

Hi Andy,

I have tested it by sending a single ping to a station within the VLAN 
followed by a ping to a station thats not in a VLAN.
OK, thats not really a significant test, because I did not send a VLAN tagged 
frame immediately followed by one without a tag.
You are right, this code can enable/disable VLAN  tagging before the previous 
packet is processed.


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