linux-kernel - Re: [PATCH 02/13] ACPI: CPPC: Fix doxygen comments

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Message-ID: <20210714161435.fp6z6wqvmvobynwm@bogus>
Date:   Wed, 14 Jul 2021 17:14:35 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Cristian Marussi <cristian.marussi@....com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Sudeep Holla <sudeep.holla@....com>,
        Jassi Brar <jassisinghbrar@...il.com>
Subject: Re: [PATCH 02/13] ACPI: CPPC: Fix doxygen comments

On Wed, Jul 14, 2021 at 05:07:02PM +0100, Cristian Marussi wrote:
> On Wed, Jul 14, 2021 at 04:12:10PM +0100, Sudeep Holla wrote:
> > On Wed, Jul 14, 2021 at 02:20:05PM +0200, Rafael J. Wysocki wrote:
> > > On Thu, Jul 8, 2021 at 8:09 PM Sudeep Holla <sudeep.holla@....com> wrote:
> > > >
> > > > Clang complains about doxygen comments too with W=1 in the build.
> > > >
> > > >   | drivers/acpi/cppc_acpi.c:560: warning: Function parameter or member
> > > >   |     'pcc_ss_id' not described in 'pcc_data_alloc'
> > > >   | drivers/acpi/cppc_acpi.c:1343: warning: Function parameter or member
> > > >   |     'cpu_num' not described in 'cppc_get_transition_latency'
> > > >
> > > > Fix it.
> > > >
> > > > Signed-off-by: Sudeep Holla <sudeep.holla@....com>
> > > > ---
> > > >  drivers/acpi/cppc_acpi.c | 7 +++++++
> > > >  1 file changed, 7 insertions(+)
> > > >
> > > > diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c
> > > > index a4d4eebba1da..eb5685167d19 100644
> > > > --- a/drivers/acpi/cppc_acpi.c
> > > > +++ b/drivers/acpi/cppc_acpi.c
> > > > @@ -562,6 +562,8 @@ bool __weak cpc_ffh_supported(void)
> > > >  /**
> > > >   * pcc_data_alloc() - Allocate the pcc_data memory for pcc subspace
> > > >   *
> > >
> > > I would drop this empty line (and analogously below).
> > >
> > 
> > Sure
> > 
> > > > + * @pcc_ss_id: PCC Subspace channel identifier
> > > > + *
> > > >   * Check and allocate the cppc_pcc_data memory.
> > > >   * In some processor configurations it is possible that same subspace
> > > >   * is shared between multiple CPUs. This is seen especially in CPUs
> > > > @@ -1347,10 +1349,15 @@ EXPORT_SYMBOL_GPL(cppc_set_perf);
> > > >  /**
> > > >   * cppc_get_transition_latency - returns frequency transition latency in ns
> > > >   *
> > > > + * @cpu_num: Logical index of the CPU for which latencty is requested
> > > > + *
> > > >   * ACPI CPPC does not explicitly specify how a platform can specify the
> > > >   * transition latency for performance change requests. The closest we have
> > > >   * is the timing information from the PCCT tables which provides the info
> > > >   * on the number and frequency of PCC commands the platform can handle.
> > > > + *
> > > > + * Returns: frequency transition latency on success or CPUFREQ_ETERNAL on
> > > > + * failure
> > > 
> > > Is this change needed?  The one-line summary already says this.
> > >
> >
> > Right, not required. I must have got confused with other place that expected
> > return summary.
> >
> I think kernel-doc complains if no Return: (not Returns:) doxygen clause
> is provided while describing a function which do return some values.
> (..even though the info is clearly duplicated as it is now in the
> one-line summary)
>

Thanks Cristian, just noticed the same. I was convinced that I did see the
warning before but couldn't recollect the details quickly.

$ ./scripts/kernel-doc -none drivers/acpi/cppc_acpi.c
(no warnings)

$ ./scripts/kernel-doc -v -none drivers/acpi/cppc_acpi.c 
drivers/acpi/cppc_acpi.c:1345: warning: No description found for return value of 'cppc_get_transition_latency'

The build with W=1 may not be using -v. That explains why I got confused as
I initially started with W=1 build but did switch to ./scripts/kernel-doc -v
after Joe pointed out its existence.

--
Regards,
Sudeep