Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756741AbaFWUcb (ORCPT ); Mon, 23 Jun 2014 16:32:31 -0400 Received: from mail-ob0-f177.google.com ([209.85.214.177]:62152 "EHLO mail-ob0-f177.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754504AbaFWUca (ORCPT ); Mon, 23 Jun 2014 16:32:30 -0400 MIME-Version: 1.0 In-Reply-To: <20140623202615.GA29199@kroah.com> References: <20140621180201.GA4621@amd.pavel.ucw.cz> <20140621194538.GA4903@kroah.com> <20140623130259.GA29809@amd.pavel.ucw.cz> <20140623201503.GA4551@amd.pavel.ucw.cz> <20140623202615.GA29199@kroah.com> Date: Mon, 23 Jun 2014 16:32:29 -0400 X-Google-Sender-Auth: MZvoZ0ssd6aOi6j57nUjrRJRIDE 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 Mon, Jun 23, 2014 at 4:26 PM, Greg KH wrote: > On Mon, Jun 23, 2014 at 04:18:39PM -0400, Ilia Mirkin wrote: >> On Mon, Jun 23, 2014 at 4:15 PM, Pavel Machek wrote: >> > Hi! >> > >> >> >> >> > 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? >> >> > >> >> >> Could we just say that the format of this file is one-per-line of >> >> >> >> >> >> level: information-for-the-user >> >> > >> >> > But it is not. >> >> >> >> But it is... >> >> >> >> > Management tools will want to parse it, sooner or >> >> > later. What is wrong with solution described above? >> >> >> >> It is complex and annoying to the people that will actually use it. >> > >> > grep -r . pstate/ is actually not that bad... >> >> While that's a clever trick that anyone who's done a bunch of stuff >> with sysfs knows, I doubt the average linux user could come up with >> that on their own. I know I didn't. > > That's fine, why would an "average" Linux user ever need to poke around > in sysfs? Again, please describe what you are wanting to have exported > to userspace, and what userspace is supposed to do with that > information, before worrying about the actual sysfs file layout. It would be nice to allow the end-user to switch between performance levels on the card. A particular card exposes some number of levels (well, a particular card's VBIOS), identified by a value between 0-254 (usually identified as a 2-char hex string). Each level has various information associated with it, like timing parameters for various bits of the card, as well as some more user-friendly concepts like "memory clock speed" etc. The card's current state may or may not correspond to one of the predefined levels; often-times the VBIOS initializes the card into some non-level state. This state may also be of some interest to the user. We can't switch to arbitrary speeds, only the defined ones (because of the various other timing parameters). The level ids don't carry too much semantic value (higher usually means faster though), so it would additionally be nice to tell the user some of the more user-friendly information about each level. Different hardware versions will be able to expose different types of information (but always in pairs). -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/