linux-kernel - Re: [PATCH 5/5] iio: stmpe-adc: Reset possible interrupts

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Date:   Mon, 13 May 2019 07:47:14 +0000
From:   Philippe Schenker <philippe.schenker@...adex.com>
To:     "jic23@...nel.org" <jic23@...nel.org>
CC:     "linux-stm32@...md-mailman.stormreply.com" 
        <linux-stm32@...md-mailman.stormreply.com>,
        "stefan@...er.ch" <stefan@...er.ch>,
        Marcel Ziswiler <marcel.ziswiler@...adex.com>,
        "David.Laight@...LAB.COM" <David.Laight@...LAB.COM>,
        Max Krummenacher <max.krummenacher@...adex.com>,
        "linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
        "lee.jones@...aro.org" <lee.jones@...aro.org>,
        "pmeerw@...erw.net" <pmeerw@...erw.net>,
        "knaack.h@....de" <knaack.h@....de>,
        "mcoquelin.stm32@...il.com" <mcoquelin.stm32@...il.com>,
        "lars@...afoo.de" <lars@...afoo.de>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "alexandre.torgue@...com" <alexandre.torgue@...com>
Subject: Re: [PATCH 5/5] iio: stmpe-adc: Reset possible interrupts

On Sat, 2019-05-11 at 11:24 +0100, Jonathan Cameron wrote:
> On Tue,  7 May 2019 16:36:15 +0200
> Philippe Schenker <dev@...henker.ch> wrote:
> 
> > From: Philippe Schenker <philippe.schenker@...adex.com>
> > 
> > Clear any interrupt that still is on the device on every channel
> > this driver is activated for in probe and specific channels in
> > the timeout handler.
> > 
> > Signed-off-by: Philippe Schenker <philippe.schenker@...adex.com>
> I'm never particularly clean on blanket resets as they do tend to
> hide bugs. However, the probe one is something that would happen anyway
> if there was a 'reset' function.
> 
> Applied to the togreg branch of iio.git and pushed out as testing
> for the autobuilders to play with it.
> 
> Thanks,
> 
> Jonathan

You're right about hiding bugs. But if the interrupt for whatever (hardware?)
reason does not occur, it prevents further interrupts as it does not get reset.

So this reset takes care that after a timeout one is still able to read out the
ADC.

Philippe

> 
> > ---
> > 
> >  drivers/iio/adc/stmpe-adc.c | 5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/drivers/iio/adc/stmpe-adc.c b/drivers/iio/adc/stmpe-adc.c
> > index cc752a47444c..a5990e9f2c80 100644
> > --- a/drivers/iio/adc/stmpe-adc.c
> > +++ b/drivers/iio/adc/stmpe-adc.c
> > @@ -80,6 +80,8 @@ static int stmpe_read_voltage(struct stmpe_adc *info,
> >  	ret = wait_for_completion_timeout(&info->completion, STMPE_ADC_TIMEOUT);
> >  
> >  	if (ret <= 0) {
> > +		stmpe_reg_write(info->stmpe, STMPE_REG_ADC_INT_STA,
> > +				STMPE_ADC_CH(info->channel));
> >  		mutex_unlock(&info->lock);
> >  		return -ETIMEDOUT;
> >  	}
> > @@ -326,6 +328,9 @@ static int stmpe_adc_probe(struct platform_device *pdev)
> >  	stmpe_reg_write(info->stmpe, STMPE_REG_ADC_INT_EN,
> >  			~(norequest_mask & 0xFF));
> >  
> > +	stmpe_reg_write(info->stmpe, STMPE_REG_ADC_INT_STA,
> > +			~(norequest_mask & 0xFF));
> > +
> >  	return devm_iio_device_register(&pdev->dev, indio_dev);
> >  }
> >