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Date: Sat, 20 Dec 2014 21:29:12 +0000 From: "Pandruvada, Srinivas" <srinivas.pandruvada@...el.com> To: "Baluta, Daniel" <daniel.baluta@...el.com> CC: "lars@...afoo.de" <lars@...afoo.de>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "knaack.h@....de" <knaack.h@....de>, "jic23@...nel.org" <jic23@...nel.org>, "Purdila, Octavian" <octavian.purdila@...el.com>, "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>, "Westerberg, Mika" <mika.westerberg@...el.com>, "pmeerw@...erw.net" <pmeerw@...erw.net>, "beomho.seo@...sung.com" <beomho.seo@...sung.com>, "gwendal@...omium.org" <gwendal@...omium.org> Subject: Re: [RFC PATCH] iio: ak8975: Make sure chipset is always initialized +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 <knaack.h@....de> 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 <octavian.purdila@...el.com> > > >> Signed-off-by: Daniel Baluta <daniel.baluta@...el.com> > > >> --- > > >> 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. >
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