linux-kernel - Re: [PATCH 2/2] staging: sm750fb: Remove unused return value in program_mode

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Message-ID: <ZS+moqE585lPBN3m@dorcaslitunya-virtual-machine>
Date:   Wed, 18 Oct 2023 12:34:26 +0300
From:   Dorcas Litunya <anonolitunya@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     outreachy@...ts.linux.dev, julia.lawall@...ia.fr,
        dan.carpenter@...aro.org, andi.shyti@...ux.intel.com,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>,
        Teddy Wang <teddy.wang@...iconmotion.com>,
        linux-fbdev@...r.kernel.org, linux-staging@...ts.linux.dev,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] staging: sm750fb: Remove unused return value in
 program_mode_registers()

On Wed, Oct 18, 2023 at 11:26:33AM +0200, Greg Kroah-Hartman wrote:
> On Wed, Oct 18, 2023 at 12:07:38PM +0300, Dorcas AnonoLitunya wrote:
> > Modifies the return type of program_mode_registers()
> > to void from int as the return value is being ignored in
> > all subsequent function calls.
> > 
> > This improves code readability and maintainability.
> > 
> > Suggested-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> > Signed-off-by: Dorcas AnonoLitunya <anonolitunya@...il.com>
> > ---
> >  drivers/staging/sm750fb/ddk750_mode.c | 5 ++---
> >  1 file changed, 2 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/staging/sm750fb/ddk750_mode.c b/drivers/staging/sm750fb/ddk750_mode.c
> > index 83ace6cc9583..e15039238232 100644
> > --- a/drivers/staging/sm750fb/ddk750_mode.c
> > +++ b/drivers/staging/sm750fb/ddk750_mode.c
> > @@ -73,8 +73,8 @@ display_control_adjust_sm750le(struct mode_parameter *mode_param,
> >  }
> >  
> >  /* only timing related registers will be  programed */
> > -static int program_mode_registers(struct mode_parameter *mode_param,
> > -				  struct pll_value *pll)
> > +static void program_mode_registers(struct mode_parameter *mode_param,
> > +				   struct pll_value *pll)
> >  {
> >  	int ret = 0;
> >  	int cnt = 0;
> > @@ -202,7 +202,6 @@ static int program_mode_registers(struct mode_parameter *mode_param,
> >  	} else {
> >  		ret = -1;
> 
> Why are you still setting the 'ret' variable if you are not doing
> anything with it anymore?
> 
> >  	}
> > -	return ret;
> 
> Are you sure that the caller shouldn't be checking for errors instead of
> dropping the return value?  If so, document that in the changelog too.
>
Seems like the caller doesn't use the function to check for errors as in
the code below:

int ddk750_set_mode_timing(struct mode_parameter *parm, enum clock_type clock)
{
        struct pll_value pll;

        pll.input_freq = DEFAULT_INPUT_CLOCK;
        pll.clock_type = clock;

        sm750_calc_pll_value(parm->pixel_clock, &pll);
        if (sm750_get_chip_type() == SM750LE) {
                /* set graphic mode via IO method */
                outb_p(0x88, 0x3d4);
                outb_p(0x06, 0x3d5);
        }
        program_mode_registers(parm, &pll);
        return 0;

It will still return 0 regardless of whether there is an error or not.
Since I am not sure how the two functions relate to one another, is
there need to check error in the caller function?

thanks,
Dorcas
> thanks,
> 
> greg k-h