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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham 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 CF5AAC10F03 for ; Tue, 23 Apr 2019 22:20:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A41ED217D9 for ; Tue, 23 Apr 2019 22:20:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726325AbfDWWUW (ORCPT ); Tue, 23 Apr 2019 18:20:22 -0400 Received: from relay10.mail.gandi.net ([217.70.178.230]:44379 "EHLO relay10.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726075AbfDWWUV (ORCPT ); Tue, 23 Apr 2019 18:20:21 -0400 Received: from localhost (unknown [88.190.179.123]) (Authenticated sender: repk@triplefau.lt) by relay10.mail.gandi.net (Postfix) with ESMTPSA id 7133724000A; Tue, 23 Apr 2019 22:20:18 +0000 (UTC) Date: Wed, 24 Apr 2019 00:29:18 +0200 From: Remi Pommarel To: Lorenzo Pieralisi Cc: Thomas Petazzoni , Bjorn Helgaas , linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Miquel Raynal Subject: Re: [PATCH] pci: aardvark: Wait for endpoint to be ready before training link Message-ID: <20190423222917.GN2754@voidbox.localdomain> References: <20190313213752.1246-1-repk@triplefau.lt> <20190423163215.GB26523@red-moon> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190423163215.GB26523@red-moon> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Hi, On Tue, Apr 23, 2019 at 05:32:15PM +0100, Lorenzo Pieralisi wrote: > On Wed, Mar 13, 2019 at 10:37:52PM +0100, Remi Pommarel wrote: > > When configuring pcie reset pin from gpio (e.g. initially set by > > u-boot) to pcie function this pin goes low for a brief moment > > asserting the PERST# signal. Thus connected device enters fundamental > > reset process and link configuration can only begin after a minimal > > 100ms delay (see [1]). > > > > This makes sure that link is configured after at least 100ms from > > beginning of probe() callback (shortly after the reset pin function > > configuration switch through pinctrl subsytem). > > > > [1] "PCI Express Base Specification", REV. 2.1 > > PCI Express, March 4 2009, 6.6.1 Conventional Reset > > > > Signed-off-by: Remi Pommarel > > --- > > drivers/pci/controller/pci-aardvark.c | 17 ++++++++++++++--- > > 1 file changed, 14 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c > > index a30ae7cf8e7e..70a1023d0ef1 100644 > > --- a/drivers/pci/controller/pci-aardvark.c > > +++ b/drivers/pci/controller/pci-aardvark.c > > @@ -177,6 +177,9 @@ > > > > #define PIO_TIMEOUT_MS 1 > > > > +/* Endpoint can take up to 100ms to be ready after a reset */ > > +#define ENDPOINT_RST_MS 100 > > + > > #define LINK_WAIT_MAX_RETRIES 10 > > #define LINK_WAIT_USLEEP_MIN 90000 > > #define LINK_WAIT_USLEEP_MAX 100000 > > @@ -242,8 +245,10 @@ static int advk_pcie_wait_for_link(struct advk_pcie *pcie) > > return -ETIMEDOUT; > > } > > > > -static void advk_pcie_setup_hw(struct advk_pcie *pcie) > > +static void > > +advk_pcie_setup_hw(struct advk_pcie *pcie, unsigned long ep_rdy_time) > > Nit: I prefer the prototype to be in one line, I wrap it for you. > > I am wondering why you need to pass in ep_rdy_time parameter when you > can easily compute it in the function itself. > The only reason for that is because the sooner I get the jiffies the lower the delay has to be. I was trying to reduce the impact of this delay to a minimum, but maybe the improvement is not worth it. -- Remi