From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 305FFC18E7D for ; Wed, 22 May 2019 10:41:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 02C5320856 for ; Wed, 22 May 2019 10:41:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729183AbfEVKk7 (ORCPT ); Wed, 22 May 2019 06:40:59 -0400 Received: from skyboo.net ([94.40.87.198]:47838 "EHLO skyboo.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728690AbfEVKk6 (ORCPT ); Wed, 22 May 2019 06:40:58 -0400 Received: from manio by skyboo.net with local (Exim 4.91) (envelope-from ) id 1hTOg3-0003zI-Ln; Wed, 22 May 2019 12:40:56 +0200 From: Mariusz Bialonczyk To: linux-kernel@vger.kernel.org, Greg Kroah-Hartman Cc: Mariusz Bialonczyk Date: Wed, 22 May 2019 12:40:53 +0200 Message-Id: <20190522104053.14577-1-manio@skyboo.net> X-Mailer: git-send-email 2.19.0.rc1 In-Reply-To: <20190520070558.20142-3-manio@skyboo.net> References: <20190520070558.20142-3-manio@skyboo.net> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: X-SA-Exim-Rcpt-To: linux-kernel@vger.kernel.org, greg@kroah.com, manio@skyboo.net X-SA-Exim-Mail-From: manio@skyboo.net Subject: [PATCH 3/4 v2] w1: ds2413: when the slave is not responding during read, select it again X-SA-Exim-Version: 4.2.1 (built Tue, 02 Aug 2016 21:08:31 +0000) X-SA-Exim-Scanned: Yes (on skyboo.net) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The protocol is not allowing to obtain a byte of 0xff for PIO_ACCESS_READ call. It is very likely that the slave was not addressed properly and it is just not respoding (leaving the bus in logic high state) during the read of sampled PIO value. We cannot just call w1_reset_resume_command() because the problem will persist, instead try selecting (addressing) the slave again. Signed-off-by: Mariusz Bialonczyk --- Changes in v2: Optimize the if statement so the most common is checked first. drivers/w1/slaves/w1_ds2413.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/drivers/w1/slaves/w1_ds2413.c b/drivers/w1/slaves/w1_ds2413.c index d63778c70568..21f08ac8a4e0 100644 --- a/drivers/w1/slaves/w1_ds2413.c +++ b/drivers/w1/slaves/w1_ds2413.c @@ -24,6 +24,7 @@ #define W1_F3A_FUNC_PIO_ACCESS_READ 0xF5 #define W1_F3A_FUNC_PIO_ACCESS_WRITE 0x5A #define W1_F3A_SUCCESS_CONFIRM_BYTE 0xAA +#define W1_F3A_INVALID_PIO_STATE 0xFF static ssize_t state_read(struct file *filp, struct kobject *kobj, struct bin_attribute *bin_attr, char *buf, loff_t off, @@ -45,6 +46,7 @@ static ssize_t state_read(struct file *filp, struct kobject *kobj, mutex_lock(&sl->master->bus_mutex); dev_dbg(&sl->dev, "mutex locked"); +next: if (w1_reset_select_slave(sl)) goto out; @@ -52,10 +54,15 @@ static ssize_t state_read(struct file *filp, struct kobject *kobj, w1_write_8(sl->master, W1_F3A_FUNC_PIO_ACCESS_READ); *buf = w1_read_8(sl->master); - /* check for correct complement */ if ((*buf & 0x0F) == ((~*buf >> 4) & 0x0F)) { + /* complement is correct */ bytes_read = 1; goto out; + } else if (*buf == W1_F3A_INVALID_PIO_STATE) { + /* slave didn't respond, try to select it again */ + dev_warn(&sl->dev, "slave device did not respond to PIO_ACCESS_READ, " \ + "reselecting, retries left: %d\n", retries); + goto next; } if (w1_reset_resume_command(sl->master)) -- 2.19.0.rc1