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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EBCC2C3527B for ; Tue, 5 Apr 2022 20:56:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230468AbiDEU4e (ORCPT ); Tue, 5 Apr 2022 16:56:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38254 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1457655AbiDEQ0q (ORCPT ); Tue, 5 Apr 2022 12:26:46 -0400 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5CF667C166 for ; Tue, 5 Apr 2022 09:24:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1649175887; x=1680711887; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=1lT1ORduTl6wuyJso2/+MycwhVPSszvccKAqxCLmaKA=; b=EKhPDvKSZT7Sx5Ysmf0SLufYBQux87LpMX4WzBTleoSNdr9H07sDyM7h 0IQF4S2x7SY3V9BIIqflv0HArsWjFqcsRUexg41vwJd9GIlpmwEbg4/bQ TTpKidzQFInrkdsuuIepA1qlM9jy5xOnDJ6VVEpeQevGhDCge7QZPkOTb /KaSRt7WRfVDT14gLNx5fTAEVeI0QfY1eDXhcwlEBm3RL4qszEg005//1 DUEhE9LDyMn6Yp7M/XKzavessWGc7D5eHneq2Bgeqd+WSiGE5qzKxhjVI AA4/yqKimtgrx7qXuKq5179WP4gUUgITCi89ADSa6sHG52bbFSRuQArg5 Q==; X-IronPort-AV: E=McAfee;i="6200,9189,10308"; a="258378361" X-IronPort-AV: E=Sophos;i="5.90,236,1643702400"; d="scan'208";a="258378361" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Apr 2022 09:24:46 -0700 X-IronPort-AV: E=Sophos;i="5.90,236,1643702400"; d="scan'208";a="569964880" Received: from lahna.fi.intel.com (HELO lahna) ([10.237.72.162]) by orsmga008-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Apr 2022 09:24:44 -0700 Received: by lahna (sSMTP sendmail emulation); Tue, 05 Apr 2022 19:24:41 +0300 Date: Tue, 5 Apr 2022 19:24:41 +0300 From: Mika Westerberg To: Bjorn Helgaas Cc: Bjorn Helgaas , Rodrigo Vivi , linux-pci@vger.kernel.org Subject: Re: [PATCH] PCI: Quirk Intel DG2 ASPM L1 acceptable latency to be unlimited Message-ID: References: <20220405093810.76613-1-mika.westerberg@linux.intel.com> <20220405160151.GA68831@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220405160151.GA68831@bhelgaas> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Hi Bjorn, On Tue, Apr 05, 2022 at 11:01:51AM -0500, Bjorn Helgaas wrote: > On Tue, Apr 05, 2022 at 12:38:10PM +0300, Mika Westerberg wrote: > > Intel DG2 discrete graphics PCIe endpoints hard-code their acceptable L1 > > ASPM latency to be < 1us even though the hardware actually supports > > higher latencies (> 64 us) just fine. In order to allow the links to go > > into L1 and save power, quirk the acceptable L1 ASPM latency for these > > endpoints to be unlimited. > > Is there a plan to fix this in future DG2 hardware/firmware? > Obviously the point of Dev Cap is to make the device self-describing > so we can avoid updates like this every time new hardware comes out. Yes, I think that's the plan. > > Note this does not have any effect unless the user requested the kernel > > to enable ASPM in the first place (by default we don't enable it). > > I think this depends on the platform and kernel config, doesn't it? > If CONFIG_PCIEASPM_POWERSAVE=y or CONFIG_PCIEASPM_POWER_SUPERSAVE=y > I suspect we would enable ASPM L1 even without the parameters below. > > > This is done with "pcie_aspm=force pcie_aspm.policy=powersupsersave" > > command line parameters. > > s/powersupsersave/powersupersave/ > > This should affect "powersave" as well as "powersupersave", right? > Both enable L1. "powersupersave" enables the L1 substates. > > We *should* be able to enable/disable ASPM L1 using the sysfs "l1_aspm > file, too. Indeed you are right. I think we can drop that paragraph completely from the commit log. Do you want me to send v2 with that corrected or you will do that while applying? Thanks!