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=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 41399C35280 for ; Mon, 30 Sep 2019 15:40:46 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D975E206BB for ; Mon, 30 Sep 2019 15:40:45 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="itWisQxQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D975E206BB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=+Dhdz809vEsQPKy4sPBQuZKPOvbZjOrnCqokVMb6KNU=; b=itWisQxQmOwcV4 bQW7CvJ+sd8aaOBmBj5HnqNhBQcNDfou35bbVbZUhjbgDLE4uTZEdzQwtkV6lLdgy/bj4ei6DzfRH AP+v/2oqsrj1w4pMucy49cZIitY6iBQY7sS3XGrwX8Z9/c+GV7VcAFT/1oFi+zqfdLxMMzbDe4Kyv k20rGRtD7TP1kuSikSlbR/QxFd6vlRHwAAUBtocF+TdeJSkPWlyWocB6WPEnx8EPia/UuabKFQxeO s+z6HSVC9ySJRe/SPeyI80YtYmGwbJ6ijLNq44cxuQg8YBvZR0UAgz6msbr3WDqh/IfifcALyc71A jqVemjeI56aO+S4MTong==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.2 #3 (Red Hat Linux)) id 1iExn3-0003H9-Bm; Mon, 30 Sep 2019 15:40:45 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.2 #3 (Red Hat Linux)) id 1iExmf-0002tQ-PZ for linux-arm-kernel@lists.infradead.org; Mon, 30 Sep 2019 15:40:23 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 589151000; Mon, 30 Sep 2019 08:40:20 -0700 (PDT) Received: from localhost (unknown [10.37.6.20]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C3C083F706; Mon, 30 Sep 2019 08:40:19 -0700 (PDT) Date: Mon, 30 Sep 2019 16:40:18 +0100 From: Andrew Murray To: Remi Pommarel Subject: Re: [PATCH v3] PCI: aardvark: Use LTSSM state to build link training flag Message-ID: <20190930154017.GF42880@e119886-lin.cambridge.arm.com> References: <20190522213351.21366-3-repk@triplefau.lt> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190522213351.21366-3-repk@triplefau.lt> User-Agent: Mutt/1.10.1+81 (426a6c1) (2018-08-26) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190930_084021_920562_76644ABD X-CRM114-Status: GOOD ( 25.54 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Ellie Reeves , Lorenzo Pieralisi , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, Bjorn Helgaas , Thomas Petazzoni , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, May 22, 2019 at 11:33:51PM +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 > --- > Changes since v1: > - Rename retraining flag field > - Fix DEVCTL register writing > > Changes since v2: > - Rewrite patch logic so it is more legible > > Please note that I will unlikely be able to answer any comments from May > 24th to June 10th. > --- > drivers/pci/controller/pci-aardvark.c | 29 ++++++++++++++++++++++++++- > 1 file changed, 28 insertions(+), 1 deletion(-) > > diff --git a/drivers/pci/controller/pci-aardvark.c b/drivers/pci/controller/pci-aardvark.c > index 134e0306ff00..8803083b2174 100644 > --- a/drivers/pci/controller/pci-aardvark.c > +++ b/drivers/pci/controller/pci-aardvark.c > @@ -180,6 +180,8 @@ > #define LINK_WAIT_MAX_RETRIES 10 > #define LINK_WAIT_USLEEP_MIN 90000 > #define LINK_WAIT_USLEEP_MAX 100000 > +#define RETRAIN_WAIT_MAX_RETRIES 10 > +#define RETRAIN_WAIT_USLEEP_US 2000 > > #define MSI_IRQ_NUM 32 > > @@ -239,6 +241,17 @@ static int advk_pcie_wait_for_link(struct advk_pcie *pcie) > return -ETIMEDOUT; > } > > +static void advk_pcie_wait_for_retrain(struct advk_pcie *pcie) > +{ > + size_t retries; > + > + for (retries = 0; retries < RETRAIN_WAIT_MAX_RETRIES; ++retries) { > + if (!advk_pcie_link_up(pcie)) > + break; > + udelay(RETRAIN_WAIT_USLEEP_US); > + } > +} > + > static void advk_pcie_setup_hw(struct advk_pcie *pcie) > { > u32 reg; > @@ -426,11 +439,20 @@ advk_pci_bridge_emul_pcie_conf_read(struct pci_bridge_emul *bridge, > return PCI_BRIDGE_EMUL_HANDLED; > } > > + case PCI_EXP_LNKCTL: { > + /* u32 contains both PCI_EXP_LNKCTL and PCI_EXP_LNKSTA */ > + u32 val = advk_readl(pcie, PCIE_CORE_PCIEXP_CAP + reg) & > + ~(PCI_EXP_LNKSTA_LT << 16); The commit message says "the flag is always set to 0" - therefore I guess you don't *need* to mask out the LT bit here? I assume this is just belt-and-braces but thought I'd check incase I've misunderstood or if your commit message is inaccurate. In any case masking out the bit (or adding a comment) makes this code more readable as the reader doesn't need to know what the hardware does with this bit. > + if (!advk_pcie_link_up(pcie)) > + val |= (PCI_EXP_LNKSTA_LT << 16); > + *value = val; > + return PCI_BRIDGE_EMUL_HANDLED; > + } > + > case PCI_CAP_LIST_ID: > case PCI_EXP_DEVCAP: > case PCI_EXP_DEVCTL: > case PCI_EXP_LNKCAP: > - case PCI_EXP_LNKCTL: > *value = advk_readl(pcie, PCIE_CORE_PCIEXP_CAP + reg); > return PCI_BRIDGE_EMUL_HANDLED; > default: > @@ -447,8 +469,13 @@ advk_pci_bridge_emul_pcie_conf_write(struct pci_bridge_emul *bridge, > > switch (reg) { > case PCI_EXP_DEVCTL: > + advk_writel(pcie, new, PCIE_CORE_PCIEXP_CAP + reg); > + break; Why is this here? Thanks, Andrew Murray > + > case PCI_EXP_LNKCTL: > advk_writel(pcie, new, PCIE_CORE_PCIEXP_CAP + reg); > + if (new & PCI_EXP_LNKCTL_RL) > + advk_pcie_wait_for_retrain(pcie); > break; > > case PCI_EXP_RTCTL: > -- > 2.20.1 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel