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Date:   Wed, 10 Feb 2021 16:48:10 +0200
From:   Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To:     "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc:     "Rafael J. Wysocki" <rafael@kernel.org>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Len Brown <lenb@kernel.org>,
        Calvin Johnson <calvin.johnson@oss.nxp.com>
Subject: Re: [PATCH v1 7/7] ACPI: property: Allow counting a single value as
 an array of 1 element
Message-ID: <YCPyKjO7XPBFAgbn@smile.fi.intel.com>
References: <20210210114320.3478-1-andriy.shevchenko@linux.intel.com>
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 <1946478.1QpZic6vku@kreacher>
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Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
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On Wed, Feb 10, 2021 at 02:48:09PM +0100, Rafael J. Wysocki wrote:
> On Wednesday, February 10, 2021 2:31:48 PM CET Rafael J. Wysocki wrote:
> > On Wednesday, February 10, 2021 1:36:00 PM CET Rafael J. Wysocki wrote:
> > > On Wed, Feb 10, 2021 at 12:51 PM Andy Shevchenko
> > > <andriy.shevchenko@linux.intel.com> wrote:

Rafael, thanks for the review, my answers below.

> > > > We allow to read the single value as a first element in the array.
> > > > Unfortunately the counting doesn't work in this case and we can't
> > > > call fwnode_property_count_*() API without getting an error.
> > > 
> > > It would be good to mention what the symptom of the issue is here.

fwnode_property_match_string() is not working as reported by Calvin.

> > > > Modify acpi_data_prop_read() to always try the single value read
> > > > and thus allow counting the single value as an array of 1 element.
> > > >
> > > > Reported-by: Calvin Johnson <calvin.johnson@oss.nxp.com>
> > > > Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> > > 
> > > This is a bug fix, so it should go in before the cleanups in this series IMO.

Seems it was never worked, hence neither Fixes tag nor...

> > > Also it looks like stable@vger material.

...Cc to stable@.

> > > > -       if (val && nval == 1) {
> > > > +       /* Try to read as a single value first */
> > > > +       if (!val || nval == 1) {
> > > >                 ret = acpi_data_prop_read_single(data, propname, proptype, val);
> > > 
> > > This returns -EINVAL if val is NULL.

Nope. That's why it's a patch 7. Patch 6 solves this.

> > > >                 if (ret >= 0)
> > > > -                       return ret;
> > > > +                       return val ? ret : 1;
> > > 
> > > So val cannot be NULL here.

Why not? I have changed conditional.

> > > >         }

> > > To me, acpi_fwnode_property_read_string_array() needs to special-case
> > > val == NULL and nval == 0.

nval can be anything in the case of val==NULL. So far neither of your proposals
conform this.


-- 
With Best Regards,
Andy Shevchenko