Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755940AbaFWQHj (ORCPT ); Mon, 23 Jun 2014 12:07:39 -0400 Received: from out1-smtp.messagingengine.com ([66.111.4.25]:55422 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753835AbaFWQHi (ORCPT ); Mon, 23 Jun 2014 12:07:38 -0400 X-Sasl-enc: v2154CZirzbGwE/9d7lILu6ywlCGEwYeTTJOVSpuxwRi 1403539657 Date: Mon, 23 Jun 2014 12:07:27 -0400 From: Greg KH To: Ilia Mirkin Cc: Pavel Machek , kernel list , Ben Skeggs , Alexandre Courbot , David Airlie , "dri-devel@lists.freedesktop.org" Subject: Re: unparseable, undocumented /sys/class/drm/.../pstate Message-ID: <20140623160727.GA19557@kroah.com> References: <20140621180201.GA4621@amd.pavel.ucw.cz> <20140621194538.GA4903@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jun 22, 2014 at 10:12:14PM -0400, Ilia Mirkin wrote: > 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. sysfs files are "one value per file", that's it. Do anything other than that, and it can not be in sysfs, sorry. greg k-h -- 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/