linux-kernel - Re: [PATCH 1/7] clk: actions: Fix factor clk struct member access

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Date:   Mon, 10 Jun 2019 21:35:55 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Andreas Färber <afaerber@...e.de>
Cc:     sboyd@...nel.org, ulf.hansson@...aro.org, robh+dt@...nel.org,
        linux-arm-kernel@...ts.infradead.org, linux-mmc@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        thomas.liau@...ions-semi.com, linux-actions@...ts.infradead.org,
        linus.walleij@...aro.org, linux-clk@...r.kernel.org
Subject: Re: [PATCH 1/7] clk: actions: Fix factor clk struct member access


Hi Andreas,

On Mon, Jun 10, 2019 at 03:36:42PM +0200, Andreas Färber wrote:
> Hi Mani,
> 
> Am 08.06.19 um 21:53 schrieb Manivannan Sadhasivam:
> > Since the helper "owl_factor_helper_round_rate" is shared between factor
> > and composite clocks, using the factor clk specific helper function
> > like "hw_to_owl_factor" to access its members will create issues when
> > called from composite clk specific code. Hence, pass the "factor_hw"
> > struct pointer directly instead of fetching it using factor clk specific
> > helpers.
> > 
> > This issue has been observed when a composite clock like "sd0_clk" tried
> > to call "owl_factor_helper_round_rate" resulting in pointer dereferencing
> > error.
> > 
> > Fixes: 4bb78fc9744a ("clk: actions: Add factor clock support")
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > ---
> >  drivers/clk/actions/owl-factor.c | 7 +++----
> >  1 file changed, 3 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/clk/actions/owl-factor.c b/drivers/clk/actions/owl-factor.c
> > index 317d4a9e112e..f419dfdd334f 100644
> > --- a/drivers/clk/actions/owl-factor.c
> > +++ b/drivers/clk/actions/owl-factor.c
> > @@ -64,11 +64,10 @@ static unsigned int _get_table_val(const struct clk_factor_table *table,
> >  	return val;
> >  }
> >  
> > -static int clk_val_best(struct clk_hw *hw, unsigned long rate,
> > +static int clk_val_best(const struct owl_factor_hw *factor_hw,
> > +			struct clk_hw *hw, unsigned long rate,
> >  			unsigned long *best_parent_rate)
> >  {
> > -	struct owl_factor *factor = hw_to_owl_factor(hw);
> > -	struct owl_factor_hw *factor_hw = &factor->factor_hw;
> >  	const struct clk_factor_table *clkt = factor_hw->table;
> >  	unsigned long parent_rate, try_parent_rate, best = 0, cur_rate;
> >  	unsigned long parent_rate_saved = *best_parent_rate;
> > @@ -126,7 +125,7 @@ long owl_factor_helper_round_rate(struct owl_clk_common *common,
> >  	const struct clk_factor_table *clkt = factor_hw->table;
> >  	unsigned int val, mul = 0, div = 1;
> >  
> > -	val = clk_val_best(&common->hw, rate, parent_rate);
> > +	val = clk_val_best(factor_hw, &common->hw, rate, parent_rate);
> >  	_get_table_div_mul(clkt, val, &mul, &div);
> >  
> >  	return *parent_rate * mul / div;
> 
> While at it, I think it would be a good idea to rename it to
> owl_clk_val_best. Pretty confusing that you're touching only owl files
> for a clk_ refactoring, which sounds like common clk code.
> 

Sure, will do.

Thanks,
Mani

> Regards,
> Andreas
> 
> -- 
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