From mboxrd@z Thu Jan 1 00:00:00 1970 From: Richard Cochran Subject: Re: [PATCH v2 1/1] net: fec: ptp: avoid register access when ipg clock is disabled Date: Thu, 14 Aug 2014 10:42:51 +0200 Message-ID: <20140814084251.GC7555@netboy> References: <1407905705-27984-1-git-send-email-b38611@freescale.com> <1407905705-27984-2-git-send-email-b38611@freescale.com> <20140813211941.GB4840@netboy> <4dcf48cd1c11473c82fcec0c8963ece2@BLUPR03MB373.namprd03.prod.outlook.com> <20140814081036.GB7555@netboy> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "shawn.guo@linaro.org" , "davem@davemloft.net" , "netdev@vger.kernel.org" To: "fugang.duan@freescale.com" Return-path: Received: from mail-wi0-f178.google.com ([209.85.212.178]:32839 "EHLO mail-wi0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752196AbaHNInF (ORCPT ); Thu, 14 Aug 2014 04:43:05 -0400 Received: by mail-wi0-f178.google.com with SMTP id hi2so1928224wib.5 for ; Thu, 14 Aug 2014 01:43:00 -0700 (PDT) Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Thu, Aug 14, 2014 at 08:24:39AM +0000, fugang.duan@freescale.com wrote: > 1. HW ptp is one feature of FEC IP, when the ethx interface is closed, ptp slave cannot sync with master, > So the ptp timer is not accurate, of couse there have discontinuities in ptp clock. No, it just becomes a free running clock. This is no different than the Linux system clock. It keeps running, even if ntpd is not. > 2. When the ethx net interface is closed, FEC IP clocks are disabled, access ptp counter register causes > Hw hang. Well, then, you need to return an error, don't you? > 3. PTP is not separate HW IP, which is one hw feature of FEC IP, when the net interface is closed, user > Call clock_gettime() is not reasonable. Yes, it is. See #1. Thanks, Richard