linux-kernel - Re: [PATCH] cpufreq: s3c64xx: Remove pointless NULL check in s3c64xx_cpufreq_driver

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Message-ID: <20191023165417.GA15082@ubuntu-m2-xlarge-x86>
Date:   Wed, 23 Oct 2019 09:54:17 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>,
        Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com
Subject: Re: [PATCH] cpufreq: s3c64xx: Remove pointless NULL check in
 s3c64xx_cpufreq_driver_init

On Wed, Oct 23, 2019 at 05:36:56PM +0100, Mark Brown wrote:
> On Wed, Oct 23, 2019 at 09:26:28AM -0700, Nathan Chancellor wrote:
> > On Wed, Oct 23, 2019 at 11:43:04AM +0100, Mark Brown wrote:
> 
> > > The driver should also have supported s3c6400 as well.
> 
> > Kconfig says otherwise, unless I am missing something.
> 
> > config ARM_S3C64XX_CPUFREQ
> >         bool "Samsung S3C64XX"
> >         depends on CPU_S3C6410
> >         default y
> >         help
> >           This adds the CPUFreq driver for Samsung S3C6410 SoC.
> > 
> >           If in doubt, say N.
> 
> Note the XX in the config option.

But what about the depends and the help text?

If I just enable the following config options in multi_v7_defconfig and
remove that depends, the driver will not build because the {dvfs,freq}_table
definitions only get added to the final source file when CONFIG CPU_S3C6410 is
set...

CONFIG_ARCH_MULTI_V6=y
CONFIG_ARCH_S3C64XX=y
CONFIG_MACH_SMDK6400=y

  CC      drivers/cpufreq/s3c64xx-cpufreq.o
../drivers/cpufreq/s3c64xx-cpufreq.c:61:13: error: use of undeclared identifier 's3c64xx_freq_table'
        new_freq = s3c64xx_freq_table[index].frequency;
                   ^
../drivers/cpufreq/s3c64xx-cpufreq.c:62:29: error: use of undeclared identifier 's3c64xx_freq_table'
        dvfs = &s3c64xx_dvfs_table[s3c64xx_freq_table[index].driver_data];
                                   ^
../drivers/cpufreq/s3c64xx-cpufreq.c:62:10: error: use of undeclared identifier 's3c64xx_dvfs_table'
        dvfs = &s3c64xx_dvfs_table[s3c64xx_freq_table[index].driver_data];
                ^
...
14 errors generated.

So maybe it _should_ support s3c6400 but it does not appear to, which
is why there is this clang warning that my patch is trying to address.

If I am missing something critical, please let me know.

Cheers,
Nathan