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=-5.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 F0697C352AB for ; Fri, 27 Sep 2019 08:34:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C358F2075D for ; Fri, 27 Sep 2019 08:34:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726498AbfI0IeY (ORCPT ); Fri, 27 Sep 2019 04:34:24 -0400 Received: from relay1-d.mail.gandi.net ([217.70.183.193]:47353 "EHLO relay1-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725911AbfI0IeX (ORCPT ); Fri, 27 Sep 2019 04:34:23 -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 relay1-d.mail.gandi.net (Postfix) with ESMTPSA id 9C4DA24000C; Fri, 27 Sep 2019 08:34:21 +0000 (UTC) Date: Fri, 27 Sep 2019 10:34:20 +0200 From: Thomas Petazzoni To: Remi Pommarel Cc: Lorenzo Pieralisi , Bjorn Helgaas , linux-pci@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] PCI: aardvark: Don't rely on jiffies while holding spinlock Message-ID: <20190927103420.48bb9335@windsurf> In-Reply-To: <20190927083142.8571-1-repk@triplefau.lt> References: <20190927083142.8571-1-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, Thanks for the new iteration! On Fri, 27 Sep 2019 10:31:42 +0200 Remi Pommarel wrote: > diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c > index fc0fe4d4de49..ee05ccb2b686 100644 > --- a/drivers/pci/controller/pci-aardvark.c > +++ b/drivers/pci/controller/pci-aardvark.c > @@ -175,7 +175,8 @@ > (PCIE_CONF_BUS(bus) | PCIE_CONF_DEV(PCI_SLOT(devfn)) | \ > PCIE_CONF_FUNC(PCI_FUNC(devfn)) | PCIE_CONF_REG(where)) > > -#define PIO_TIMEOUT_MS 1 > +#define PIO_RETRY_CNT 10 > +#define PIO_RETRY_DELAY 2 /* 2 us*/ So this changes the timeout from 1ms to just 20us, a division by 50 from the previous timeout value. From my measurements, it could sometime take up to 6us from a single PIO read operation to complete, which is getting close to the 20us timeout. Shouldn't PIO_RETRY_CNT be kept at 500, so that we keep using a 1ms timeout ? Thomas -- Thomas Petazzoni, CTO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com