From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933504AbbJIQTp (ORCPT ); Fri, 9 Oct 2015 12:19:45 -0400 Received: from unicorn.mansr.com ([81.2.72.234]:38086 "EHLO unicorn.mansr.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933474AbbJIQTn convert rfc822-to-8bit (ORCPT ); Fri, 9 Oct 2015 12:19:43 -0400 From: =?iso-8859-1?Q?M=E5ns_Rullg=E5rd?= To: Rob Herring Cc: Mark Rutland , Rob Herring , Pawel Moll , Ian Campbell , Kumar Gala , "devicetree\@vger.kernel.org" , "linux-kernel\@vger.kernel.org" Subject: Re: [PATCH v2 1/2] devicetree: add binding for generic mmio clocksource References: <1444232234-2133-1-git-send-email-mans@mansr.com> <20151007154727.GC28981@leverpostej> Date: Fri, 09 Oct 2015 17:19:40 +0100 In-Reply-To: (=?iso-8859-1?Q?=22M=E5n?= =?iso-8859-1?Q?s_Rullg=E5rd=22's?= message of "Thu, 08 Oct 2015 10:24:57 +0100") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Måns Rullgård writes: > Rob Herring writes: > >> On Wed, Oct 7, 2015 at 11:47 AM, Måns Rullgård wrote: >>> What would be a proper way to select a sched_clock source? I realise >>> it's a Linux-specific thing and DT is supposed to be generic, but the >>> information must be provided somehow. >> >> The kernel already has some logic to do this. Most number of bits >> followed by highest frequency will be the winning sched_clock. You >> might also want to look at things like always on or not. > > The problem is that sched_clock_register() doesn't take a pointer to be > passed back to the read_sched_clock callback like most interfaces of > this type do. This means the callback must use global variables set up > before the register call, but at that time there's no way of knowing > which one will be used. If there were a way of getting a pointer to the > callback, it would be a simple matter of registering all instances and > letting the kernel choose which to use. Anyone got a comment on this? Do I have to send a patch adding this before anyone will tell me why it's a bad idea? (That method almost always works.) -- Måns Rullgård mans@mansr.com