linux-kernel - Re: [PATCH 07/20] media: si21xx: report eventual errors at set

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Message-ID: <20211129094041.4fec2ef0@coco.lan>
Date:   Mon, 29 Nov 2021 09:40:41 +0100
From:   Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
To:     Nathan Chancellor <nathan@...nel.org>
Cc:     linuxarm@...wei.com, mauro.chehab@...wei.com,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org
Subject: Re: [PATCH 07/20] media: si21xx: report eventual errors at
 set_frontend

Em Fri, 26 Nov 2021 12:45:23 -0700
Nathan Chancellor <nathan@...nel.org> escreveu:

> On Wed, Nov 24, 2021 at 08:13:10PM +0100, Mauro Carvalho Chehab wrote:
> > If an error occurs while setting the registers at set_frontend,
> > it is silently ignored. Yet, the variable status is updated.
> > 
> > Change the logic to return an error if it fails to write values
> > to the registers.
> > 
> > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>  
> 
> I am not super familiar with the different return codes so I assume it
> is appropriate (the sites that I see calling set_frontend() appears to
> only check for a negative return code).

There are a couple of return codes used on media when I/O transfer fails.
Some places use -EREMOTEIO. Others use -EIO or -ENXIO.

I guess -EREMOTEIO is a little bit better than -EIO for I2C transfers,
as the problem usually happened inside an I2C bus at the DVB adapter.

> 
> Reviewed-by: Nathan Chancellor <nathan@...nel.org>
> 
> > ---
> > 
> > To avoid mailbombing on a large number of people, only mailing lists were C/C on the cover.
> > See [PATCH 00/20] at: https://lore.kernel.org/all/cover.1637781097.git.mchehab+huawei@kernel.org/
> > 
> >  drivers/media/dvb-frontends/si21xx.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/media/dvb-frontends/si21xx.c b/drivers/media/dvb-frontends/si21xx.c
> > index e31eb2c5cc4c..001b23588389 100644
> > --- a/drivers/media/dvb-frontends/si21xx.c
> > +++ b/drivers/media/dvb-frontends/si21xx.c
> > @@ -711,7 +711,7 @@ static int si21xx_set_frontend(struct dvb_frontend *fe)
> >  	int i;
> >  	bool inband_interferer_div2[ALLOWABLE_FS_COUNT];
> >  	bool inband_interferer_div4[ALLOWABLE_FS_COUNT];
> > -	int status;
> > +	int status = 0;
> >  
> >  	/* allowable sample rates for ADC in MHz */
> >  	int afs[ALLOWABLE_FS_COUNT] = { 200, 192, 193, 194, 195,
> > @@ -747,8 +747,6 @@ static int si21xx_set_frontend(struct dvb_frontend *fe)
> >  	rf_freq = 10 * c->frequency ;
> >  	data_rate = c->symbol_rate / 100;
> >  
> > -	status = PASS;
> > -
> >  	band_low = (rf_freq - lnb_lo) - ((lnb_uncertanity * 200)
> >  					+ (data_rate * 135)) / 200;
> >  
> > @@ -832,6 +830,9 @@ static int si21xx_set_frontend(struct dvb_frontend *fe)
> >  	state->fs = sample_rate;/*ADC MHz*/
> >  	si21xx_setacquire(fe, c->symbol_rate, c->fec_inner);
> >  
> > +	if (status)
> > +		return -EREMOTEIO;
> > +
> >  	return 0;
> >  }
> >  
> > -- 
> > 2.33.1
> > 
> >   



Thanks,
Mauro