Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762310AbYGaCyi (ORCPT ); Wed, 30 Jul 2008 22:54:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754703AbYGaCt6 (ORCPT ); Wed, 30 Jul 2008 22:49:58 -0400 Received: from SpacedOut.fries.net ([67.64.210.234]:60566 "EHLO SpacedOut.fries.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760496AbYGaCt4 (ORCPT ); Wed, 30 Jul 2008 22:49:56 -0400 Date: Wed, 30 Jul 2008 21:49:51 -0500 From: David Fries To: Andrew Morton Cc: Evgeniy Polyakov , linux-kernel@vger.kernel.org Subject: [PATCH 18/30] W1: ds1wm.c msleep for reset Message-ID: <20080731024951.GS12181@spacedout.fries.net> References: <20080729020433.GA24424@spacedout.fries.net> <20080729161356.2de456fb.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080729161356.2de456fb.akpm@linux-foundation.org> User-Agent: Mutt/1.5.4i X-Greylist: Sender is SPF-compliant, not delayed by milter-greylist-3.0 (SpacedOut.fries.net [127.0.0.1]); Wed, 30 Jul 2008 21:49:51 -0500 (CDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1653 Lines: 42 Like the previous w1_io.c reset coments and msleep patch, I don't have the hardware to verify the change, but I think it is safe. It also helps to see a comment like this in the code. "We'll wait a bit longer just to be sure." If they are going to calculate delaying 324.9us, but actually delay 500us, why not just give up the CPU and sleep? This is designed for a battery powered ARM system, avoiding busywaiting has to be good for battery life. I sent a request for testers March 7, 2008 to the Linux kernel mailing list and two developers who have patches for ds1wm.c, but I didn't get any respons. Signed-off-by: David Fries Signed-off-by: Evgeniy Polyakov --- drivers/w1/masters/ds1wm.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/drivers/w1/masters/ds1wm.c b/drivers/w1/masters/ds1wm.c index ea894bf..29e144f 100644 --- a/drivers/w1/masters/ds1wm.c +++ b/drivers/w1/masters/ds1wm.c @@ -160,8 +160,10 @@ static int ds1wm_reset(struct ds1wm_data *ds1wm_data) * 625 us - 60 us - 240 us - 100 ns = 324.9 us * * We'll wait a bit longer just to be sure. + * Was udelay(500), but if it is going to busywait the cpu that long, + * might as well come back later. */ - udelay(500); + msleep(1); ds1wm_write_register(ds1wm_data, DS1WM_INT_EN, DS1WM_INTEN_ERBF | DS1WM_INTEN_ETMT | DS1WM_INTEN_EPD | -- 1.4.4.4 -- 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/