Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751531AbaFWCMQ (ORCPT ); Sun, 22 Jun 2014 22:12:16 -0400 Received: from mail-oa0-f44.google.com ([209.85.219.44]:64398 "EHLO mail-oa0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751145AbaFWCMP (ORCPT ); Sun, 22 Jun 2014 22:12:15 -0400 MIME-Version: 1.0 In-Reply-To: <20140621194538.GA4903@kroah.com> References: <20140621180201.GA4621@amd.pavel.ucw.cz> <20140621194538.GA4903@kroah.com> Date: Sun, 22 Jun 2014 22:12:14 -0400 X-Google-Sender-Auth: ETp4TIheJfk0bwlOJ1fDhmry2Mo Message-ID: Subject: Re: unparseable, undocumented /sys/class/drm/.../pstate From: Ilia Mirkin To: Greg KH Cc: Pavel Machek , kernel list , Ben Skeggs , Alexandre Courbot , David Airlie , "dri-devel@lists.freedesktop.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jun 21, 2014 at 3:45 PM, Greg KH wrote: > On Sat, Jun 21, 2014 at 02:22:59PM -0400, Ilia Mirkin wrote: >> On Sat, Jun 21, 2014 at 2:02 PM, Pavel Machek wrote: >> > Hi! >> > >> > AFAICT, pstate file will contain something like >> > >> > 07: core 100 MHz memory 123 MHz * >> > 08: core 100-200 MHz memory 123 MHz >> > >> > ...which does not look exactly like one-value-per-file, and I'm pretty >> > sure userspace will get it wrong if it tries to parse it. Plus, I >> > don't see required documentation in Documentation/ABI. >> > >> > Should we disable it for now, so that userspace does not start >> > depending on it and we'll not have to maintain it forever? >> > >> > I guess better interface would be something like >> > >> > pstate/07/core_clock_min >> > core_clock_max >> > memory_clock_min >> > memory_clock_max >> > >> > and then pstate/active containing just the number of active state? >> > >> > Thanks, >> > Pavel >> > >> > PS: I have no nvidia, got the news at >> > >> > http://www.phoronix.com/scan.php?page=article&item=nouveau_try_linux316&num=2 >> >> FTR, this file has been in place since 3.13, and there was a different >> file before it (performance_levels), with a comparable format since >> much earlier (definitely 3.8, probably earlier). I think it's meant a >> lot more for people looking at it and echo'ing stuff to it to modify >> the levels (where supported), than for programs parsing it. Perhaps >> sysfs is the wrong place for this -- what is the right place? debugfs? > > Yes, please move it to debugfs. Could we just say that the format of this file is one-per-line of level: information-for-the-user And you can echo a level into it to switch to that level? That seems like a reasonable ABI to have... would be happy to throw it into a file somewhere... not sure where though. -ilia -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/