From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnd Bergmann Subject: Re: [PATCH 04/27] asm-generic: add legacy I/O header files Date: Fri, 1 May 2009 15:29:04 +0200 Message-ID: <200905011529.04774.arnd@arndb.de> References: <20090501123728.GC27799@flint.arm.linux.org.uk> <20090501140904.69f44406@lxorguk.ukuu.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Return-path: Received: from moutng.kundenserver.de ([212.227.126.177]:51992 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761823AbZEAN3G (ORCPT ); Fri, 1 May 2009 09:29:06 -0400 In-Reply-To: <20090501140904.69f44406@lxorguk.ukuu.org.uk> Content-Disposition: inline Sender: linux-arch-owner@vger.kernel.org List-ID: To: Alan Cox Cc: Russell King , Michal Simek , linux-arch@vger.kernel.org, Remis Lima Baima , linux-kernel@vger.kernel.org On Friday 01 May 2009, Alan Cox wrote: > Joining in late but its not at all highly PC specific. The same frequency > is used for a whole pile of setups (Alpha etc). It's not well named but > there are good sound reasons the PC chose 1193182 and while those reasons > have long lapsed its a good frequency for other reasons nowdays. > > The clock isn't for the PIC either - its for the PIT (although its used > to clock various other things). > > We actually have a define of PIT_TICK_RATE internal to the x86 port for > those x86 cases that can use it. How about this comment then: /* * CLOCK_TICK_RATE is traditionally the base frequency using the PC-style * i8253 "PIT" timer. Architecture independent device drivers should not * rely on this value. * Any architecture that either has a real PC-style PIT, or does not have a * fixed timer interval at all and just needs to provide some value here * should just fall back to this default. */ Arnd <><