From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_2 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A8A6AC4360D for ; Wed, 25 Sep 2019 12:32:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7CDAE21655 for ; Wed, 25 Sep 2019 12:32:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405479AbfIYMcE (ORCPT ); Wed, 25 Sep 2019 08:32:04 -0400 Received: from relay9-d.mail.gandi.net ([217.70.183.199]:50877 "EHLO relay9-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405285AbfIYMcE (ORCPT ); Wed, 25 Sep 2019 08:32:04 -0400 X-Originating-IP: 86.250.200.211 Received: from windsurf (lfbn-1-17395-211.w86-250.abo.wanadoo.fr [86.250.200.211]) (Authenticated sender: thomas.petazzoni@bootlin.com) by relay9-d.mail.gandi.net (Postfix) with ESMTPSA id 971A7FF80C; Wed, 25 Sep 2019 12:32:01 +0000 (UTC) Date: Wed, 25 Sep 2019 14:32:00 +0200 From: Thomas Petazzoni To: Remi Pommarel Cc: Lorenzo Pieralisi , Bjorn Helgaas , Ellie Reeves , linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] PCI: aardvark: Use LTSSM state to build link training flag Message-ID: <20190925143200.696af4cf@windsurf> In-Reply-To: <20190522213351.21366-3-repk@triplefau.lt> References: <20190522213351.21366-3-repk@triplefau.lt> Organization: Bootlin X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Remi, On Wed, 22 May 2019 23:33:51 +0200 Remi Pommarel wrote: > Aardvark's PCI_EXP_LNKSTA_LT flag in its link status register is not > implemented and does not reflect the actual link training state (the > flag is always set to 0). In order to support link re-training feature > this flag has to be emulated. The Link Training and Status State > Machine (LTSSM) flag in Aardvark LMI config register could be used as > a link training indicator. Indeed if the LTSSM is in L0 or upper state > then link training has completed (see [1]). > > Unfortunately because after asking a link retraining it takes a while > for the LTSSM state to become less than 0x10 (due to L0s to recovery > state transition delays), LTSSM can still be in L0 while link training > has not finished yet. So this waits for link to be in recovery or lesser > state before returning after asking for a link retrain. > > [1] "PCI Express Base Specification", REV. 4.0 > PCI Express, February 19 2014, Table 4-14 > > Signed-off-by: Remi Pommarel Here as well, sorry for the very long delay, and many thanks for the great research work, including the arm-trusted-firmware fix. I reviewed the implementation, and tested on my Armada 3720 DB board with a E1000E NIC, and it all looks good to me. Acked-by: Thomas Petazzoni Thanks! Thomas -- Thomas Petazzoni, CTO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com