linux-kernel - Re: [PATCH] clk: fix clk_mux_val_to

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Message-ID: <154396287588.88331.2840230818482804190@swboyd.mtv.corp.google.com>
Date:   Tue, 04 Dec 2018 14:34:35 -0800
From:   Stephen Boyd <sboyd@...nel.org>
To:     Jerome Brunet <jbrunet@...libre.com>,
        Michael Turquette <mturquette@...libre.com>
Cc:     linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: fix clk_mux_val_to_index() error value

Quoting Jerome Brunet (2018-12-04 11:55:10)
> On Tue, 2018-12-04 at 10:43 -0800, Stephen Boyd wrote:
> > Quoting Jerome Brunet (2018-12-04 08:34:03)
> > > clk_mux_val_to_index() is meant to be used by .get_parent(), which
> > > returns a u8, so when the value provided does not map to any valid index,
> > > it is not a good idea to return a negative error value.
> > > 
> > > Instead, return num_parents which we know is an invalid index and let
> > > CCF deal with it.
> > > 
> > > Fixes: 77deb66d262f ("clk: mux: add helper function for index/value
> > > translation")
> > > Signed-off-by: Jerome Brunet <jbrunet@...libre.com>
> > > ---
> > 
> > Thanks!
> > 
> > > diff --git a/include/linux/clk-provider.h b/include/linux/clk-provider.h
> > > index 60c51871b04b..fc20886ef069 100644
> > > --- a/include/linux/clk-provider.h
> > > +++ b/include/linux/clk-provider.h
> > > @@ -550,8 +550,8 @@ struct clk_hw *clk_hw_register_mux_table(struct device
> > > *dev, const char *name,
> > >                 void __iomem *reg, u8 shift, u32 mask,
> > >                 u8 clk_mux_flags, u32 *table, spinlock_t *lock);
> > >  
> > > -int clk_mux_val_to_index(struct clk_hw *hw, u32 *table, unsigned int
> > > flags,
> > > -                        unsigned int val);
> > > +u8 clk_mux_val_to_index(struct clk_hw *hw, u32 *table, unsigned int
> > > flags,
> > 
> > I wonder if we should just make this unsigned int? Does it hurt at all
> > to have it be a wider type even though it doesn't match the CCF decision
> > to make this a u8 for the parent index number space?
> > 
> 
> I also wondered about this but since the target is get_parent(), I just
> aligned the two.
> 
> In the end, I don't really care, as you prefer. Just let me know if you would
> like a v2 with this change
> 

Ok I may just make it unsigned int when applying then.