From mboxrd@z Thu Jan 1 00:00:00 1970 From: dom Subject: Re: ixgbe: Question about Flow Control on 10G Date: Wed, 15 Oct 2014 11:56:34 -0700 Message-ID: <543EC362.5060507@citrix.com> References: <543D72FE.9090107@citrix.com> <87618083B2453E4A8714035B62D67992500E1865@FMSMSX105.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit To: "Tantilov, Emil S" , "Skidmore, Donald C" , "netdev@vger.kernel.org" Return-path: Received: from smtp02.citrix.com ([66.165.176.63]:19460 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751624AbaJOS4K (ORCPT ); Wed, 15 Oct 2014 14:56:10 -0400 In-Reply-To: <87618083B2453E4A8714035B62D67992500E1865@FMSMSX105.amr.corp.intel.com> Sender: netdev-owner@vger.kernel.org List-ID: On 10/14/2014 01:54 PM, Tantilov, Emil S wrote: >> -----Original Message----- >> From: netdev-owner@vger.kernel.org [mailto:netdev- >> owner@vger.kernel.org] On Behalf Of dom >> Sent: Tuesday, October 14, 2014 12:01 PM >> To: Skidmore, Donald C; netdev@vger.kernel.org >> Subject: ixgbe: Question about Flow Control on 10G >> >> Hi >> >> I have a question about the ixgbe driver's handling of >> 'ethtool -a ethX' >> when the NIC is using fibre. >> >> Specifically I don't understand the code introduced by this >> commit: >> >> commit 73d80953dfd1d5a92948005798c857c311c2834b >> Author: Don Skidmore >> Date: Wed Jul 31 02:19:24 2013 +0000 >> Subject: ixgbe: fix fc autoneg ethtool reporting. >> >> The function introduced the function: >> ixgbe_device_supports_autoneg_fc() >> >> which gets called by >> ixgbe_get_pauseparam()/ixgbe_set_pauseparam(). >> >> specifically there is a case in >> ixgbe_device_supports_autoneg_fc() >> >> case ixgbe_media_type_fiber_qsfp: >> case ixgbe_media_type_fiber: >> hw->mac.ops.check_link(hw, &speed, &link_up, >> false); >> /* if link is down, assume supported */ >> if (link_up) >> supported = speed == IXGBE_LINK_SPEED_1GB_FULL ? >> true : false; >> >> If link_up=1 then why is supported only true for a >> speed=IXGBE_LINK_SPEED_1GB_FULL ? >> >> Why is Flow Control not supported for IXGBE_LINK_SPEED_10GB_FULL ? > For SFP modules (media_type_fiber) flow control autoneg is not supported at 10gig. You can still set flow control manually to enabled/disabled, just not autoneg. > > Thanks, > Emil Hi Emil Thank you for the quick answer. I have a one follow-up question if I may... We noticed that back in 3.2.9 (before 73d80953dfd basically) the behaviour was different for 10G fibre. i.e. autonegotiate showed 'on'. # ethtool -a eth1 Pause parameters for eth1: Autonegotiate: on RX: on TX: on The code: if (hw->fc.disable_fc_autoneg || (hw->fc.current_mode == ixgbe_fc_none)) pause->autoneg = 0; else pause->autoneg = 1; So I assume this old output from 'ethtool -a' for autogen was just wrong, is that correct ? [I'm asking cos I _know_ my h/w collegues are going to ask why the change.] Thanks again dom