From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267372AbUITVxw (ORCPT ); Mon, 20 Sep 2004 17:53:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267374AbUITVxw (ORCPT ); Mon, 20 Sep 2004 17:53:52 -0400 Received: from atlrel6.hp.com ([156.153.255.205]:61136 "EHLO atlrel6.hp.com") by vger.kernel.org with ESMTP id S267372AbUITVxs (ORCPT ); Mon, 20 Sep 2004 17:53:48 -0400 From: Bjorn Helgaas To: Christoph Lameter Subject: Re: device driver for the SGI system clock, mmtimer Date: Mon, 20 Sep 2004 15:53:29 -0600 User-Agent: KMail/1.7 Cc: Vojtech Pavlik , Jesse Barnes , linux-kernel@vger.kernel.org, Bob Picco , venkatesh.pallipadi@intel.com, Andrew Morton References: <200409161003.39258.bjorn.helgaas@hp.com> <20040916181426.GA5052@ucw.cz> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200409201553.29824.bjorn.helgaas@hp.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thursday 16 September 2004 12:46 pm, Christoph Lameter wrote: > On Thu, 16 Sep 2004, Vojtech Pavlik wrote: > > mmtimer and hpet are the same hardware actually, just a different > > specification revision, hpet being the newer one. > > Its basically the same software API but different hardware. OK, I guess I'm convinced that the SGI mmtimer and the HPET really are different things. It looks like the counter resolution, frequency, and size (which are all described in the HPET register set) are either compiled into mmtimer or discovered via special- purpose SGI hooks. So maybe it's not really a good thing to integrate mmtimer and hpet. Apps that mmap the HPET will be expecting a certain register layout that mmtimer doesn't support. I was confused because your mmtimer patch mentions the Intel spec, and the driver identifies itself as "IA-PC Multimedia Timer". My vote would be to leave mmtimer alone, and perhaps remove the references to the Intel spec and change the driver ident string. After all, it doesn't really implement very much of the HPET functionality, and I don't think the Intel spec says anything that relates to the SGI hardware.