linux-kernel - Re: [PATCH v2 1/2] hwspinlock: sprd: fixed warning of unused variable 'sprd_hwspinlock_of

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Date:   Mon, 2 Nov 2020 17:58:24 -0600
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Baolin Wang <baolin.wang7@...il.com>
Cc:     Chunyan Zhang <zhang.lyra@...il.com>,
        Ohad Ben-Cohen <ohad@...ery.com>,
        "linux-remoteproc@...r.kernel.org" <linux-remoteproc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Orson Zhai <orsonzhai@...il.com>,
        Chunyan Zhang <chunyan.zhang@...soc.com>
Subject: Re: [PATCH v2 1/2] hwspinlock: sprd: fixed warning of unused
 variable 'sprd_hwspinlock_of_match'

On Mon 02 Nov 17:34 CST 2020, Baolin Wang wrote:

> On Friday, October 30, 2020, Chunyan Zhang <zhang.lyra@...il.com> wrote:
> > From: Chunyan Zhang <chunyan.zhang@...soc.com>
> >
> > The macro function of_match_ptr() is NULL if CONFIG_OF is not set, then
> > Clang compiler would complain the of_device_id variable is unused.
> >
> > But using of_match_ptr() is space saving, for this case, the unused
> structure
> > 'sprd_hwspinlock_of_match' would be not built into symbol table if
> CONFIG_OF
> > is not set, probably depends on the compiler though.
> >
> > So adding __maybe_unsed seems a good approach to fix this warning.
> >
> > Reported-by: kernel test robot <lkp@...el.com>
> > Fixes: d8c8bbbb1aba ("hwspinlock: sprd: Add hardware spinlock driver")
> > Signed-off-by: Chunyan Zhang <chunyan.zhang@...soc.com>
> > ---
> 
> I'd like to remove this wrapper, and just depend on the CONFIG_OF. But I
> have no objection for this patch.  So
> Reviewed-by: Baolin Wang <baolin.wang7@...il.com>
> 

As noted on the first line of the probe function, this driver isn't
going to do anything when CONFIG_OF is disabled - and I don't think we
should worry too much about space savings during COMPILE_TEST.

So I would prefer that we simply drop the of_match_ptr()

But I believe that's what you're saying as well Baolin?

Regards,
Bjorn

> 
> >  drivers/hwspinlock/sprd_hwspinlock.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/hwspinlock/sprd_hwspinlock.c
> b/drivers/hwspinlock/sprd_hwspinlock.c
> > index 36dc8038bbb4..4c63e2546064 100644
> > --- a/drivers/hwspinlock/sprd_hwspinlock.c
> > +++ b/drivers/hwspinlock/sprd_hwspinlock.c
> > @@ -138,7 +138,7 @@ static int sprd_hwspinlock_probe(struct
> platform_device *pdev)
> >                                          SPRD_HWLOCKS_NUM);
> >  }
> >
> > -static const struct of_device_id sprd_hwspinlock_of_match[] = {
> > +static const __maybe_unused struct of_device_id
> sprd_hwspinlock_of_match[] = {
> >         { .compatible = "sprd,hwspinlock-r3p0", },
> >         { /* sentinel */ }
> >  };
> > --
> > 2.20.1
> >
> >
> 
> -- 
> Baolin Wang