From mboxrd@z Thu Jan 1 00:00:00 1970 From: Martin Mokrejs Subject: Re: suspended DRAM bridge Date: Mon, 01 Apr 2013 23:09:09 +0200 Message-ID: <5159F775.30805@fold.natur.cuni.cz> References: <5159BAC9.80700@fold.natur.cuni.cz> <35938665.ZFvDxnCU3l@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: Received: from fold.natur.cuni.cz ([195.113.57.32]:43400 "HELO fold.natur.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1757666Ab3DAVJN (ORCPT ); Mon, 1 Apr 2013 17:09:13 -0400 In-Reply-To: <35938665.ZFvDxnCU3l@vostro.rjw.lan> Sender: linux-pm-owner@vger.kernel.org List-Id: linux-pm@vger.kernel.org To: "Rafael J. Wysocki" Cc: Linux PM list Hi Rafael, Rafael J. Wysocki wrote: > On Monday, April 01, 2013 06:50:17 PM Martin Mokrejs wrote: >> Hi Rafael, >> I have a simple question. Why seems my DRAM controller suspended? > > I suppose that runtime PM is disabled for that device and therefore > runtime_status is meaningless. But I really mean this pair of values: /sys/bus/pci/devices/0000:00:00.0/power/runtime_status:suspended /sys/bus/pci/devices/0000:00:00.0/power/control:auto > > And really, that attribute is for *debugging* things by developers who know > what they are looking for and not for random poking. Well, if me or you are to figure out why laptop-mode-tools make my life even more miserable with hotplug issues the requests to provide grep . /sys/bus/pci/devices/*/power/runtime_status grep . /sys/bus/pci/devices/*/power/control provide crap. How can I infer something if I cannot trust the values? Don't you think that this is the reason why you have a headache and me as well? Seriously, only pcieport driver reports PME# enabled/disabled messages in my system although find /sys/bus/pci/devices/*/power/ -name control | while read f; do echo on > $f; done should trigger similar message from other drivers as well! Provided they are somewhat equally verbose under same kernel debug level. But they are all silent. And if I start to think what the values mean it looks silly my only DRAM controller is suspended. I really do think that devices which cannot be ever suspended under a particular condition should not claim they are suspended if they did not. I reported that I sometimes see only PME# enabled (or just disabled) in dmesg from a same device in dmesg *NOT* the accompanied opposite action on the same device. As I see that most of my pci devices do not ever report a change of their status I was hoping /sys/bus/pci/devices/*/power/runtime_status is correct. > > Besides, this is a host bridge, not a DRAM controller. Hmm. > >> Does it make any sense in a laptop computer? How could the laptop work at all? > > I suppose it wouldn't work if the PCI host bridge were suspended. At least > it couldn't access memory and the PCI bus then. Thank you, had the same, although naive, expectation. Thanks, Martin