Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752495AbaLTVkW (ORCPT ); Sat, 20 Dec 2014 16:40:22 -0500 Received: from mail-wi0-f172.google.com ([209.85.212.172]:39272 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751187AbaLTVkU convert rfc822-to-8bit (ORCPT ); Sat, 20 Dec 2014 16:40:20 -0500 MIME-Version: 1.0 In-Reply-To: <1419110952.2843.8.camel@spandruv-hsb-test> References: <1418923002-901-1-git-send-email-daniel.baluta@intel.com> <5494A3D6.60607@gmx.de> <1419110796.2843.6.camel@spandruv-hsb-test> <1419110952.2843.8.camel@spandruv-hsb-test> Date: Sat, 20 Dec 2014 23:40:18 +0200 X-Google-Sender-Auth: x9PGcqm0M5aJGKN8BOy5ZFBPg-Q Message-ID: Subject: Re: [RFC PATCH] iio: ak8975: Make sure chipset is always initialized From: Daniel Baluta To: "Pandruvada, Srinivas" Cc: "Baluta, Daniel" , "lars@metafoo.de" , "linux-kernel@vger.kernel.org" , "knaack.h@gmx.de" , "jic23@kernel.org" , "Purdila, Octavian" , "linux-iio@vger.kernel.org" , "Westerberg, Mika" , "pmeerw@pmeerw.net" , "beomho.seo@samsung.com" , "gwendal@chromium.org" Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I will have closer look on why acpi_match_device could fail. This patch was only based on code reading when trying to fix the compiler warning mentioned in the commit message. [Sorry for top posting] On Sat, Dec 20, 2014 at 11:29 PM, Pandruvada, Srinivas wrote: > +Mika > > On Sat, 2014-12-20 at 13:26 -0800, Srinivas Pandruvada wrote: >> On Sat, 2014-12-20 at 00:25 +0200, Daniel Baluta wrote: >> > On Sat, Dec 20, 2014 at 12:16 AM, Hartmut Knaack wrote: >> > > Daniel Baluta schrieb am 18.12.2014 um 18:16: >> > >> When using ACPI, if acpi_match_device fails then chipset enum will be >> > >> uninitialized and &ak_def_array[chipset] will point to some bad address. >> > >> >> I am missing something. You are enumerated over i2c device, which was >> created from ACPI PNP resource. There is a valid handle or and the >> device has an ACPI companion at the least. If this failing, I have to >> check the code for acpi i2c. >> Can you check why this check failed? We may have bug in i2c handling. >> >> Thanks, >> Srinivas >> >> > >> This fixes the following compilation warning: >> > >> >> > >> drivers/iio/magnetometer/ak8975.c: In function ‘ak8975_probe’: >> > >> drivers/iio/magnetometer/ak8975.c:788:14: warning: ‘chipset’ may be used >> > >> uninitialized in this function [-Wmaybe-uninitialized] >> > >> data->def =ak_def_array[chipset]; >> > >> >> > >> Reported-by: Octavian Purdila >> > >> Signed-off-by: Daniel Baluta >> > >> --- >> > >> This is a RFC because while I'm pretty sure that chipset should be initialized >> > >> with AK_MAX_TYPE in ak8975_match_acpi_device, I am not sure if we can live with >> > >> a NULL return value of ak8975_match_acpi_device. Current implementation ignores >> > >> return value of ak8975_match_acpi_device. >> > > This seems to be the actual problem: these _match_acpi_device functions return >> > > NULL on failure, and this should be checked for. >> > >> > Ok, so this would acceptable? >> > >> > diff --git a/drivers/iio/magnetometer/ak8975.c >> > b/drivers/iio/magnetometer/ak8975.c >> > index 0d10a4b..68d99e9 100644 >> > --- a/drivers/iio/magnetometer/ak8975.c >> > +++ b/drivers/iio/magnetometer/ak8975.c >> > @@ -776,8 +776,9 @@ static int ak8975_probe(struct i2c_client *client, >> > name = id->name; >> > } else if (ACPI_HANDLE(&client->dev)) >> > name = ak8975_match_acpi_device(&client->dev, &chipset); >> > - else >> > - return -ENOSYS; >> > + >> > + if (!name) >> > + return -ENODEV; >> > >> > >> > I still have some doubts about return code in case of error. >> > >> > For ak8975 we use -ENOSYS, but for kxcjk-1013 we use -ENODEV. >> > >> > I will send a patch after we clear this out. >> > >> > thanks, >> > Daniel. >> > -- 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/