linux-kernel - Re: [PATCH] soc/tegra: refactor soc_is

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Date:   Wed, 21 Nov 2018 22:47:42 +0800
From:   Frank Lee <tiny.windzz@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>
Cc:     jonathanh@...dia.com, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] soc/tegra: refactor soc_is_tegra()

On Wed, Nov 21, 2018 at 10:43 PM Thierry Reding
<thierry.reding@...il.com> wrote:
>
> On Wed, Nov 21, 2018 at 02:34:57PM +0000, Jon Hunter wrote:
> >
> > On 21/11/2018 14:12, Yangtao Li wrote:
> > > of_find_node_by_path() acquires a reference to the node returned by
> > > it and that reference needs to be dropped by its caller.soc_is_tegra()
> > > doesn't do that, so fix it.Call of_machine_is_compatible() to refactor
> > > soc_is_tegra() whcih automatically manages the reference count.
> > >
> > > Signed-off-by: Yangtao Li <tiny.windzz@...il.com>
> > > ---
> > >  drivers/soc/tegra/common.c | 12 +++++++-----
> > >  1 file changed, 7 insertions(+), 5 deletions(-)
> > >
> > > diff --git a/drivers/soc/tegra/common.c b/drivers/soc/tegra/common.c
> > > index cd8f41351add..0b40700b672a 100644
> > > --- a/drivers/soc/tegra/common.c
> > > +++ b/drivers/soc/tegra/common.c
> > > @@ -22,11 +22,13 @@ static const struct of_device_id tegra_machine_match[] = {
> > >
> > >  bool soc_is_tegra(void)
> > >  {
> > > -   struct device_node *root;
> > > +   struct of_device_id *match = tegra_machine_match;
> > >
> > > -   root = of_find_node_by_path("/");
> > > -   if (!root)
> > > -           return false;
> > > +   while(match->compatible){
> > > +           if(of_machine_is_compatible(match->compatible))
> > > +                   return true;
> > > +           match++;
> > > +   }
> > >
> > > -   return of_match_node(tegra_machine_match, root) != NULL;
> > > +   return false;
> > >  }
> >
> > Ugh ... sorry, I thought that of_machine_is_compatible() looped through
> > the matches. OK, let's stick with your initial fix.
>
> Actually I prefer this one. Even if it is slightly more verbose, I think
> it's much clearer what's actually going on. Also this hides all of the
> OF node reference counting in a core function, so it's worth the extra
> line, in my opinion.
>
> Thierry
Hi Jon：

I like both, how aboout you?

Yours，
    Yangtao