From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Kirsher Subject: Re: [E1000-devel] [PATCH net-next] igb: add delay to allow igb loopback test to succeed on 8086:10c9 Date: Wed, 01 Aug 2012 18:06:49 -0700 Message-ID: <1343869609.2132.2.camel@jtkirshe-mobl> References: <1343821463-18052-1-git-send-email-sassmann@kpanic.de> Reply-To: jeffrey.t.kirsher@intel.com Mime-Version: 1.0 Content-Type: multipart/signed; micalg="pgp-sha512"; protocol="application/pgp-signature"; boundary="=-PHMFn7byRSejreI8pDGr" Cc: netdev@vger.kernel.org, e1000-devel@lists.sourceforge.net To: Stefan Assmann Return-path: Received: from mga14.intel.com ([143.182.124.37]:34183 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751455Ab2HBBGw (ORCPT ); Wed, 1 Aug 2012 21:06:52 -0400 In-Reply-To: <1343821463-18052-1-git-send-email-sassmann@kpanic.de> Sender: netdev-owner@vger.kernel.org List-ID: --=-PHMFn7byRSejreI8pDGr Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2012-08-01 at 13:44 +0200, Stefan Assmann wrote: > Some 8086:10c9 NICs have a problem completing the ethtool loopback > test. > The result looks like this: >=20 > ethtool -t eth1 > The test result is FAIL > The test extra info: > Register test (offline) 0 > Eeprom test (offline) 0 > Interrupt test (offline) 0 > Loopback test (offline) 13 > Link test (on/offline) 0 >=20 > A bisect clearly points to commit > a95a07445ee97a2fef65befafbadcc30ca1bd145. > However that seems to only trigger the bug. While adding some printk > the > problem disappeared, so this might be a timing issue. After some trial > and > error I discovered that adding a small delay just before > igb_write_phy_reg() > in igb_integrated_phy_loopback() allows the loopback test to succeed. > I was unable to figure out the root cause so far but I expect it to be > somewhere in the following executing path > igb_integrated_phy_loopback > ->igb_write_phy_reg_igp > ->igb_write_phy_reg_mdic > ->igb_acquire_phy_82575 > ->igb_acquire_swfw_sync_82575 >=20 > As this workaround only introduces a minor delay, which is not in the > hot > path I hope this is acceptable. The problem could only be oberved on > 8086:10c9 NICs so far and not all of them show the behaviour. I did > not > restrict the workaround to this type of NIC as it should do no harm to > other igb NICs. >=20 > With the patch below the loopback test succeeded 500 times in a row > using a NIC that would otherwise fail. >=20 > Signed-off-by: Stefan Assmann > --- > drivers/net/ethernet/intel/igb/igb_ethtool.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-)=20 Thanks Stefan, I have added the patch to my queue. --=-PHMFn7byRSejreI8pDGr Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAABCgAGBQJQGdKpAAoJEOVv75VaS+3OoNgP/R5WZgKxShxDIz5U57bO60Kr MIad6+JgVfiCnduoC/0lcdPco76mVmdYdXN8vJl6pwxbgrxqDp31ASdYH/cFpDh/ bntzebYMNmWgt0n0pqvzeH4PappWqBBFt31va7L16dCMsIVdH68wXOSP3waxZ2BV OtdYkQ3kDkH90Y2Ykloer/Fhb2pIoSAE9s9NMAf6FVZkXzPzauk3mWy6i4q20iHN 5cyc/6dwU9YvznVl3aTznWPqJSHIsnpugKpiDl4skJbqQ4PK60L0GduKyVVLjvMT 43LquWy9S5KOdKTj+zOq2BOHyzdNQsQaW+JME2ryMZB2+fwcHi2FvyQI9jtXiPKm k/OSCnXTvOqUCeKwyke9vJLFmU9RxeZ7Sb5D1nLYHH/VSrWC50jXzkdtSvDU+E0+ aJIhK07DpGKAlnwvKogBNAPhMcAjpJV+8hgZTQmbgvRDBnkzijmd0u5ysQuHpXdV LBY2wMKDkUguqmGAWWoUO6LRtUtRlspJpB2RwaCwh5iczpyRGUxYMtk8cebiE0ay cz1hQev9GNL2iahiuVkhU9mH3NaRMwdldVTrVcMhTJqxk0Wu79bPOZ1rCLJVjluP yZ6Eq0KtJG5ymH7H0CwhksNvwV9Wl4MVCc7fPLlz+Xc1sWKq7EU//X4RLvasAeoH s7yV1gtNlESIXPq+snG9 =PooR -----END PGP SIGNATURE----- --=-PHMFn7byRSejreI8pDGr--