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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 C0CF5C3A589 for ; Tue, 20 Aug 2019 10:34:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8FEE722CF9 for ; Tue, 20 Aug 2019 10:34:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566297245; bh=fqZuIvFM37lgb6CiOIy9O+jXrPlA0PzgurhoIR5df9I=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=r+ZWujFrmRIhw7lHPTsWe3lW19cAgsuQ+2ITJyQEHu6PzQaJHb3dl4ofxBn0+Z03C uZ+cwxtHpF0DTrcTfyb1karb1YviQB6adt1+BHuVjzdFnXiHoEsxWChD915joWTa7P eIudDdL4qwp7OanEGf4hrd9cJHqevbJpav8pjkdk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729464AbfHTKeF (ORCPT ); Tue, 20 Aug 2019 06:34:05 -0400 Received: from mail.kernel.org ([198.145.29.99]:47712 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728545AbfHTKeE (ORCPT ); Tue, 20 Aug 2019 06:34:04 -0400 Received: from localhost (unknown [69.71.4.100]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B3C2122CE3; Tue, 20 Aug 2019 10:34:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1566297243; bh=fqZuIvFM37lgb6CiOIy9O+jXrPlA0PzgurhoIR5df9I=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=KvH8USIbd/m91IV5FEvEhY+FTAsrpOezOk7ev3r9AWNS7XmzujWXr0ncRDE4flczC Ruz3WY2LcSnqMpH6vw+gt3rNnSyMuIAsg2EblVjBv0dfnhnAXUsx2gG02hq7CGk0DY SsvCiFLS8mY77E66Nhmr/+RuZRGQ1acWa41x3C9A= Date: Tue, 20 Aug 2019 05:34:00 -0500 From: Bjorn Helgaas To: Heiner Kallweit Cc: Frederick Lawler , "linux-pci@vger.kernel.org" , Greg KH , Rajat Jain Subject: Re: [PATCH 3/3] PCI/ASPM: add sysfs attribute for controlling ASPM Message-ID: <20190820103400.GY253360@google.com> References: <7a6d2f14-f2a6-99ad-3a93-fdaa0726ce86@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 [+cc Greg, Rajat] On Thu, May 23, 2019 at 10:05:35PM +0200, Heiner Kallweit wrote: > Background of this extension is a problem with the r8169 network driver. > Several combinations of board chipsets and network chip versions have > problems if ASPM is enabled, therefore we have to disable ASPM per default. > However especially on notebooks ASPM can provide significant power-saving, > therefore we want to give users the option to enable ASPM. With the new sysfs > attribute users can control which ASPM link-states are enabled/disabled. > > Signed-off-by: Heiner Kallweit > --- > Documentation/ABI/testing/sysfs-bus-pci | 13 ++ > drivers/pci/pci.h | 8 +- > drivers/pci/pcie/aspm.c | 180 +++++++++++++++++++++++- > 3 files changed, 193 insertions(+), 8 deletions(-) > > diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci > index 8bfee557e..38fe358de 100644 > --- a/Documentation/ABI/testing/sysfs-bus-pci > +++ b/Documentation/ABI/testing/sysfs-bus-pci > @@ -347,3 +347,16 @@ Description: > If the device has any Peer-to-Peer memory registered, this > file contains a '1' if the memory has been published for > use outside the driver that owns the device. > + > +What: /sys/bus/pci/devices/.../power/aspm_link_states > +Date: May 2019 > +Contact: Heiner Kallweit > +Description: > + If ASPM is supported for an endpoint, then this file can be > + used to enable / disable link states. A link state > + displayed in brackets is enabled, otherwise it's disabled. > + To control link states (case insensitive): > + +state : enables a supported state > + -state : disables a state > + none : disables all link states > + all : enables all supported link states IIUC this "aspm_link_states" file will contain things like this: L0S L1 L1.1 L1.2 # All states supported, all disabled [L0S] L1 # L0s enabled, L1 supported but disabled [L0S] [L1] # L0s and L1 enabled ... and the control is by writing things like this to it: +L1 # enables L1 +L1.1 # enables L1.1 -L0S # disables L0s I know this file structure is similar to protocol handling in drivers/media/rc/rc-main.c, but Documentation/filesystems/sysfs.txt suggests single values in a file, and Greg recently pointed out that we screwed up some PCI AER stats [1]. So I'm thinking maybe we should split this into several files, e.g., /sys/devices/pci*/.../power/aspm_l0s /sys/devices/pci*/.../power/aspm_l1 /sys/devices/pci*/.../power/aspm_l1.1 /sys/devices/pci*/.../power/aspm_l1.2 which would contain just 1/0 values, and we'd write 1/0 to enable/disable things. Since the L1 PM Substates control register has separate enable bits for PCI-PM L1.1 and L1.2, we might also want a way to manage those. Bjorn [1] https://lore.kernel.org/r/20190621072911.GA21600@kroah.com