Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754022Ab3JGXmV (ORCPT ); Mon, 7 Oct 2013 19:42:21 -0400 Received: from mail.active-venture.com ([67.228.131.205]:53076 "EHLO mail.active-venture.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751613Ab3JGXmT (ORCPT ); Mon, 7 Oct 2013 19:42:19 -0400 X-Originating-IP: 108.223.40.66 Message-ID: <525346D3.30500@roeck-us.net> Date: Mon, 07 Oct 2013 16:42:11 -0700 From: Guenter Roeck User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.0 MIME-Version: 1.0 To: Henrik Rydberg CC: Chris Murphy , Josh Boyer , khali@linux-fr.org, lm-sensors@lm-sensors.org, "Linux-Kernel@Vger. Kernel. Org" Subject: Re: applesmc oops in 3.10/3.11 References: <20130927175926.GA6267@roeck-us.net> <524615B1.6000106@roeck-us.net> <4FFB3671-DDB4-40F7-BA5D-C9AA9391BDA9@colorremedies.com> <524A4384.4040403@roeck-us.net> <20131002035156.GA566@roeck-us.net> <20131002095339.GA2716@polaris.bitmath.org> <524C1FE1.4050207@roeck-us.net> <20131002163418.GA4557@polaris.bitmath.org> <20131002164718.GA7392@roeck-us.net> <20131002172410.GA381@polaris.bitmath.org> In-Reply-To: <20131002172410.GA381@polaris.bitmath.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2349 Lines: 75 On 10/02/2013 10:24 AM, Henrik Rydberg wrote: >>From 4451da32414080bd0563ee9e061f19bf90463cc5 Mon Sep 17 00:00:00 2001 > From: Henrik Rydberg > Date: Wed, 2 Oct 2013 19:15:03 +0200 > Subject: [PATCH] applesmc remedy take 2 > > Conjectured problem: there are remnant bytes ready on the data line > which corrupts the read after a failure. > > Remedy: assuming bit0 is the read valid line, try to flush it before > starting a new command. > > Tests by Chris suggests reading the status is enough for the problem > to go away, which is consistent with a change in the SMC interface, > where the number of bytes to read is no longer specified, but found > out by reading until end of data. > > Tested on a MacBookAir3,1, but the original problem has not been > reproduced. So, what should we do with this patch ? Apply it ? Thanks, Guenter > --- > drivers/hwmon/applesmc.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/drivers/hwmon/applesmc.c b/drivers/hwmon/applesmc.c > index 98814d1..c0ff350 100644 > --- a/drivers/hwmon/applesmc.c > +++ b/drivers/hwmon/applesmc.c > @@ -230,6 +230,7 @@ static int send_argument(const char *key) > > static int read_smc(u8 cmd, const char *key, u8 *buffer, u8 len) > { > + u8 status, data; > int i; > > if (send_command(cmd) || send_argument(key)) { > @@ -237,6 +238,7 @@ static int read_smc(u8 cmd, const char *key, u8 *buffer, u8 len) > return -EIO; > } > > + /* This has no effect on newer (2012) SMCs */ > if (send_byte(len, APPLESMC_DATA_PORT)) { > pr_warn("%.4s: read len fail\n", key); > return -EIO; > @@ -250,6 +252,17 @@ static int read_smc(u8 cmd, const char *key, u8 *buffer, u8 len) > buffer[i] = inb(APPLESMC_DATA_PORT); > } > > + /* Read the data port until bit0 is cleared */ > + for (i = 0; i < 16; i++) { > + udelay(APPLESMC_MIN_WAIT); > + status = inb(APPLESMC_CMD_PORT); > + if (!(status & 0x01)) > + break; > + data = inb(APPLESMC_DATA_PORT); > + } > + if (i) > + pr_warn("flushed %d bytes, last value is: %d\n", i, data); > + > return 0; > } > > -- 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/