From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753259AbbBYRMZ (ORCPT ); Wed, 25 Feb 2015 12:12:25 -0500 Received: from mail.linn.co.uk ([195.59.102.251]:51505 "EHLO mail.linn.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752492AbbBYRMY (ORCPT ); Wed, 25 Feb 2015 12:12:24 -0500 Message-ID: <54EE0268.2040201@linn.co.uk> Date: Wed, 25 Feb 2015 17:12:08 +0000 From: Stathis Voukelatos User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.4.0 MIME-Version: 1.0 To: Richard Cochran CC: , , Subject: Re: [PATCH net-next v4 0/3] Linn Ethernet Packet Sniffer driver References: <20150225151945.GB7703@localhost.localdomain> <20150225170127.GD7703@localhost.localdomain> In-Reply-To: <20150225170127.GD7703@localhost.localdomain> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.2.10.132] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Richard, On 25/02/15 17:01, Richard Cochran wrote: > On Wed, Feb 25, 2015 at 04:19:45PM +0100, Richard Cochran wrote: >> Let me suggest another approach that stays in line with the existing >> frame work. Based on the device's limitations and your own example, >> it seems clear that the intended use case is synchronization for AVB >> applications using gPTP. > > Also, forgot to say, expose your clock as a PTP Hardware Clock (PHC). > Regarding this last point, the actual counter that generates the timestamps is not part of the sniffer H/W module. Timestamps are provided to the sniffer externally in H/W by a different module. Apart of that there is not eg. a sniffer register to read the current counter value. I wonder if it should be the driver for the module where the counter belongs (called Event Timer in the Pistachio Soc) that should register the PHC. I need some more time to study your other suggestions regarding the PHY timestamping framework. > Thanks, > Richard > Regards, Stathis