Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760504AbZFMWcq (ORCPT ); Sat, 13 Jun 2009 18:32:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754501AbZFMWci (ORCPT ); Sat, 13 Jun 2009 18:32:38 -0400 Received: from moutng.kundenserver.de ([212.227.126.188]:60609 "EHLO moutng.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753250AbZFMWch (ORCPT ); Sat, 13 Jun 2009 18:32:37 -0400 From: Arnd Bergmann To: liqin.chen@sunplusct.com Subject: Re: [PATCH 06/27] score: create head files delay.h device.h div64.h dma-mapping.h dma.h Date: Sun, 14 Jun 2009 00:31:54 +0200 User-Agent: KMail/1.11.90 (Linux/2.6.30-8-generic; KDE/4.2.85; x86_64; ; ) Cc: Andrew Morton , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, torvalds@linux-foundation.org References: In-Reply-To: X-Face: I@=L^?./?$U,EK.)V[4*>`zSqm0>65YtkOe>TFD'!aw?7OVv#~5xd\s,[~w]-J!)|%=]> =?utf-8?q?+=0A=09=7EohchhkRGW=3F=7C6=5FqTmkd=5Ft=3FLZC=23Q-=60=2E=60Y=2Ea=5E?= =?utf-8?q?3zb?=) =?utf-8?q?+U-JVN=5DWT=25cw=23=5BYo0=267C=26bL12wWGlZi=0A=09=7EJ=3B=5Cwg?= =?utf-8?q?=3B3zRnz?=,J"CT_)=\H'1/{?SR7GDu?WIopm.HaBG=QYj"NZD_[zrM\Gip^U MIME-Version: 1.0 Content-Type: Text/Plain; charset="gb2312" Content-Transfer-Encoding: 8bit Message-Id: <200906140031.55091.arnd@arndb.de> X-Provags-ID: V01U2FsdGVkX18wZLM7Jvd1SmKtEJrGXxs2odDdxEskeBSDGFZ zfrOyANY9V/i8Ki5wbMBcfp0mTafjvim20CuOIbXoOKgZAeV/y E++zZb5Y+jqSM5M0u2jx3w+L81NG98y Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1328 Lines: 42 On Saturday 13 June 2009, liqin.chen@sunplusct.com wrote: > Arnd Bergmann ะด?? 2009-06-10 01:18:20: > > > On Tuesday 09 June 2009, liqin.chen@sunplusct.com wrote: > > > > Having a working udelay() function is required for many > > drivers that are sensitive to timing, you should probably > > implement that at some point in the future. > > Add udelay() implement in code. so you use static inline void __delay(unsigned long loops) { __asm__ __volatile__ ( "1:\tsubi\t%0,1\n\t" "cmpz.c\t%0\n\t" "bne\t1b\n\t" : "=r" (loops) : "0" (loops)); } static inline void __udelay(unsigned long usecs) { __delay(usecs); } This is much better than before, but is far from exact in the __udelay() case. Please take a look at init/calibrate.c and how other architectures use loops_per_jiffy if you don't have an exact time source you can use. If you have a time source with microsecond resolution or better, just loop until the amount of microseconds has expired. Arnd <>< -- 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/