Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760803AbYGKN5W (ORCPT ); Fri, 11 Jul 2008 09:57:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759050AbYGKNsY (ORCPT ); Fri, 11 Jul 2008 09:48:24 -0400 Received: from zbr.yandex.ru ([213.180.219.33]:34984 "EHLO gavana.yandex.ru" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1759380AbYGKNry (ORCPT ); Fri, 11 Jul 2008 09:47:54 -0400 From: Evgeniy Polyakov To: linux-kernel@vger.kernel.org Cc: Andrew Morton , David Fries , Evgeniy Polyakov Subject: [PATCH 17/30] W1: w1_io.c reset comments and msleep Date: Fri, 11 Jul 2008 17:51:32 +0400 Message-Id: <12157843063356-git-send-email-johnpol@2ka.mipt.ru> X-Mailer: git-send-email 1.5.2.5 In-Reply-To: <12157843054074-git-send-email-johnpol@2ka.mipt.ru> References: <12157843054074-git-send-email-johnpol@2ka.mipt.ru> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1893 Lines: 52 w1_reset_bus, added some comments about the timing and switched to msleep for the later delay. I don't have the hardware to test the sleep after reset change. The one wire doesn't have a timing requirement between commands so it is fine. I do have the USB hardware and it would be in big trouble with 10ms interrupt transfers to find that the reset completed. Signed-off-by: David Fries Signed-off-by: Evgeniy Polyakov --- drivers/w1/w1_io.c | 14 +++++++++++++- 1 files changed, 13 insertions(+), 1 deletions(-) diff --git a/drivers/w1/w1_io.c b/drivers/w1/w1_io.c index a2f0d5f..dd2ecef 100644 --- a/drivers/w1/w1_io.c +++ b/drivers/w1/w1_io.c @@ -293,12 +293,24 @@ int w1_reset_bus(struct w1_master *dev) result = dev->bus_master->reset_bus(dev->bus_master->data) & 0x1; else { dev->bus_master->write_bit(dev->bus_master->data, 0); + /* minimum 480, max ? us + * be nice and sleep, except 18b20 spec lists 960us maximum, + * so until we can sleep with microsecond accuracy, spin. + * Feel free to come up with some other way to give up the + * cpu for such a short amount of time AND get it back in + * the maximum amount of time. + */ w1_delay(480); dev->bus_master->write_bit(dev->bus_master->data, 1); w1_delay(70); result = dev->bus_master->read_bit(dev->bus_master->data) & 0x1; - w1_delay(410); + /* minmum 70 (above) + 410 = 480 us + * There aren't any timing requirements between a reset and + * the following transactions. Sleeping is safe here. + */ + /* w1_delay(410); min required time */ + msleep(1); } return result; -- 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/