linux-kernel - Re: [PATCH] iio: adc: sc27xx: Add ADC data conversion timeout

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Date:   Sun, 11 Nov 2018 16:03:00 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Baolin Wang <baolin.wang@...aro.org>
Cc:     Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        freeman.liu@...soc.com, Mark Brown <broonie@...nel.org>,
        linux-iio@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iio: adc: sc27xx: Add ADC data conversion timeout

On Sun, 11 Nov 2018 23:00:18 +0800
Baolin Wang <baolin.wang@...aro.org> wrote:

> Hi Jonathan,
> 
> On 11 November 2018 at 20:40, Jonathan Cameron <jic23@...nel.org> wrote:
> > On Fri,  9 Nov 2018 11:25:31 +0800
> > Baolin Wang <baolin.wang@...aro.org> wrote:
> >  
> >> From: Freeman Liu <freeman.liu@...soc.com>
> >>
> >> Sometimes the ADC controller met some problems, and it will not complete
> >> the data conversion, that will can not wake up the read process any more
> >> to block users. So we should add one maximum conversion time to avoid
> >> this issue.
> >>
> >> Signed-off-by: Freeman Liu <freeman.liu@...soc.com>
> >> Signed-off-by: Baolin Wang <baolin.wang@...aro.org>  
> > Hi.
> >
> > Patch looks good, but sounds like this is a fix so could I have a fixes
> > tag and a patch title that makes that clear?
> >
> > I think we will want this one back ported to stable by the sound of it.
> >
> > If it is just a theoretical issue then perhaps we don't need to bother.  
> 
> Thanks for your review. This patch is not one bug fix, just make the
> code more robust in case of some bad cases. So I think we do not need
> the stable tag.
Thanks.

Applied to the togreg branch of iio.git and pushed out as testing for
the autobuilders to play with it.

Jonathan

> 
> >
> > Thanks,
> >
> > Jonathan
> >  
> >> ---
> >>  drivers/iio/adc/sc27xx_adc.c |   12 +++++++++++-
> >>  1 file changed, 11 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/iio/adc/sc27xx_adc.c b/drivers/iio/adc/sc27xx_adc.c
> >> index 7940b23..f7f7a189 100644
> >> --- a/drivers/iio/adc/sc27xx_adc.c
> >> +++ b/drivers/iio/adc/sc27xx_adc.c
> >> @@ -52,6 +52,9 @@
> >>  /* Timeout (ms) for the trylock of hardware spinlocks */
> >>  #define SC27XX_ADC_HWLOCK_TIMEOUT    5000
> >>
> >> +/* Timeout (ms) for ADC data conversion according to ADC datasheet */
> >> +#define SC27XX_ADC_RDY_TIMEOUT               100
> >> +
> >>  /* Maximum ADC channel number */
> >>  #define SC27XX_ADC_CHANNEL_MAX               32
> >>
> >> @@ -223,7 +226,14 @@ static int sc27xx_adc_read(struct sc27xx_adc_data *data, int channel,
> >>       if (ret)
> >>               goto disable_adc;
> >>
> >> -     wait_for_completion(&data->completion);
> >> +     ret = wait_for_completion_timeout(&data->completion,
> >> +                             msecs_to_jiffies(SC27XX_ADC_RDY_TIMEOUT));
> >> +     if (!ret) {
> >> +             dev_err(data->dev, "read ADC data timeout\n");
> >> +             ret = -ETIMEDOUT;
> >> +     } else {
> >> +             ret = 0;
> >> +     }
> >>
> >>  disable_adc:
> >>       regmap_update_bits(data->regmap, data->base + SC27XX_ADC_CTL,  
> >  
> 
> 
>