[PATCH v2 1/2] iio: adc: at91: fix acking DRDY irq on simple conversions

[PATCH v2 1/2] iio: adc: at91: fix acking DRDY irq on simple conversions

[Eugen Hristev]

When doing simple conversions, the driver did not acknowledge the DRDY irq.
If this irq status is not acked, it will be left pending, and as soon as a
trigger is enabled, the irq handler will be called, it doesn't know why
this status has occurred because no channel is pending, and then it will go
int a irq loop and board will hang.
To avoid this situation, read the LCDR after a raw conversion is done.

Fixes 0e589d5fb ("ARM: AT91: IIO: Add AT91 ADC driver.")
Cc: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
Hello Jonathan,

I moved this LCDR read/acknowledge into the IRQ handler after the conversion
value is being read.
Sorry about the noise to stable@vger, removed from message.

Thanks,
Eugen

 drivers/iio/adc/at91_adc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
index 44b5168..e3be88e 100644
--- a/drivers/iio/adc/at91_adc.c
+++ b/drivers/iio/adc/at91_adc.c
@@ -279,6 +279,8 @@ static void handle_adc_eoc_trigger(int irq, struct iio_dev *idev)
 		iio_trigger_poll(idev->trig);
 	} else {
 		st->last_value = at91_adc_readl(st, AT91_ADC_CHAN(st, st->chnb));
+		/* Needed to ACK the DRDY interruption */
+		at91_adc_readl(st, AT91_ADC_LCDR);
 		st->done = true;
 		wake_up_interruptible(&st->wq_data_avail);
 	}
-- 
2.7.4

[PATCH v2 2/2] iio: adc: at91: fix wrong channel number in triggered buffer mode

[Eugen Hristev]

When channels are registered, the hardware channel number is not the
actual iio channel number.
This is because the driver is probed with a certain number of accessible
channels. Some pins are routed and some not, depending on the description of
the board in the DT.
Because of that, channels 0,1,2,3 can correspond to hardware channels
2,3,4,5 for example.
In the buffered triggered case, we need to do the translation accordingly.
Fixed the channel number to stop reading the wrong channel.

Fixes 0e589d5fb "ARM: AT91: IIO: Add AT91 ADC driver."
Cc: Maxime Ripard <maxime.ripard@bootlin.com>
Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
Changes in v2:
- Added 'const' spec to the declaration to avoid build warning

 drivers/iio/adc/at91_adc.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
index e3be88e..75d2f73 100644
--- a/drivers/iio/adc/at91_adc.c
+++ b/drivers/iio/adc/at91_adc.c
@@ -248,12 +248,14 @@ static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
 	struct iio_poll_func *pf = p;
 	struct iio_dev *idev = pf->indio_dev;
 	struct at91_adc_state *st = iio_priv(idev);
+	struct iio_chan_spec const *chan;
 	int i, j = 0;
 
 	for (i = 0; i < idev->masklength; i++) {
 		if (!test_bit(i, idev->active_scan_mask))
 			continue;
-		st->buffer[j] = at91_adc_readl(st, AT91_ADC_CHAN(st, i));
+		chan = idev->channels + i;
+		st->buffer[j] = at91_adc_readl(st, AT91_ADC_CHAN(st, chan->channel));
 		j++;
 	}
 
-- 
2.7.4

Re: [PATCH v2 2/2] iio: adc: at91: fix wrong channel number in triggered buffer mode

[Jonathan Cameron]

On Mon, 24 Sep 2018 10:51:44 +0300
Eugen Hristev <eugen.hristev@microchip.com> wrote:

> When channels are registered, the hardware channel number is not the
> actual iio channel number.
> This is because the driver is probed with a certain number of accessible
> channels. Some pins are routed and some not, depending on the description of
> the board in the DT.
> Because of that, channels 0,1,2,3 can correspond to hardware channels
> 2,3,4,5 for example.
> In the buffered triggered case, we need to do the translation accordingly.
> Fixed the channel number to stop reading the wrong channel.
> 
> Fixes 0e589d5fb "ARM: AT91: IIO: Add AT91 ADC driver."
> Cc: Maxime Ripard <maxime.ripard@bootlin.com>
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Again.  Looks entirely sensible to me, but I'd like to leave it
a little longer for Maxime to have an opportunity to comment.
(or anyone else for that matter!)

Do give me a poke if I seem to have forgotten this in a week or so
though.

Thanks,

Jonathan

> ---
> Changes in v2:
> - Added 'const' spec to the declaration to avoid build warning
> 
>  drivers/iio/adc/at91_adc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
> index e3be88e..75d2f73 100644
> --- a/drivers/iio/adc/at91_adc.c
> +++ b/drivers/iio/adc/at91_adc.c
> @@ -248,12 +248,14 @@ static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
>  	struct iio_poll_func *pf = p;
>  	struct iio_dev *idev = pf->indio_dev;
>  	struct at91_adc_state *st = iio_priv(idev);
> +	struct iio_chan_spec const *chan;
>  	int i, j = 0;
>  
>  	for (i = 0; i < idev->masklength; i++) {
>  		if (!test_bit(i, idev->active_scan_mask))
>  			continue;
> -		st->buffer[j] = at91_adc_readl(st, AT91_ADC_CHAN(st, i));
> +		chan = idev->channels + i;
> +		st->buffer[j] = at91_adc_readl(st, AT91_ADC_CHAN(st, chan->channel));
>  		j++;
>  	}
>  

Re: [PATCH v2 2/2] iio: adc: at91: fix wrong channel number in triggered buffer mode

[Ludovic Desroches]

On Mon, Sep 24, 2018 at 10:51:44AM +0300, Eugen Hristev wrote:
> When channels are registered, the hardware channel number is not the
> actual iio channel number.
> This is because the driver is probed with a certain number of accessible
> channels. Some pins are routed and some not, depending on the description of
> the board in the DT.
> Because of that, channels 0,1,2,3 can correspond to hardware channels
> 2,3,4,5 for example.
> In the buffered triggered case, we need to do the translation accordingly.
> Fixed the channel number to stop reading the wrong channel.
> 
> Fixes 0e589d5fb "ARM: AT91: IIO: Add AT91 ADC driver."
> Cc: Maxime Ripard <maxime.ripard@bootlin.com>
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>

> ---
> Changes in v2:
> - Added 'const' spec to the declaration to avoid build warning
> 
>  drivers/iio/adc/at91_adc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
> index e3be88e..75d2f73 100644
> --- a/drivers/iio/adc/at91_adc.c
> +++ b/drivers/iio/adc/at91_adc.c
> @@ -248,12 +248,14 @@ static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
>  	struct iio_poll_func *pf = p;
>  	struct iio_dev *idev = pf->indio_dev;
>  	struct at91_adc_state *st = iio_priv(idev);
> +	struct iio_chan_spec const *chan;
>  	int i, j = 0;
>  
>  	for (i = 0; i < idev->masklength; i++) {
>  		if (!test_bit(i, idev->active_scan_mask))
>  			continue;
> -		st->buffer[j] = at91_adc_readl(st, AT91_ADC_CHAN(st, i));
> +		chan = idev->channels + i;
> +		st->buffer[j] = at91_adc_readl(st, AT91_ADC_CHAN(st, chan->channel));
>  		j++;
>  	}
>  
> -- 
> 2.7.4
> 

Re: [PATCH v2 2/2] iio: adc: at91: fix wrong channel number in triggered buffer mode

[Jonathan Cameron]

On Tue, 25 Sep 2018 15:17:57 +0200
Ludovic Desroches <ludovic.desroches@microchip.com> wrote:

> On Mon, Sep 24, 2018 at 10:51:44AM +0300, Eugen Hristev wrote:
> > When channels are registered, the hardware channel number is not the
> > actual iio channel number.
> > This is because the driver is probed with a certain number of accessible
> > channels. Some pins are routed and some not, depending on the description of
> > the board in the DT.
> > Because of that, channels 0,1,2,3 can correspond to hardware channels
> > 2,3,4,5 for example.
> > In the buffered triggered case, we need to do the translation accordingly.
> > Fixed the channel number to stop reading the wrong channel.
> > 
> > Fixes 0e589d5fb "ARM: AT91: IIO: Add AT91 ADC driver."
> > Cc: Maxime Ripard <maxime.ripard@bootlin.com>
> > Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>  
> Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>

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

Thanks,

Jonathan

> 
> > ---
> > Changes in v2:
> > - Added 'const' spec to the declaration to avoid build warning
> > 
> >  drivers/iio/adc/at91_adc.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
> > index e3be88e..75d2f73 100644
> > --- a/drivers/iio/adc/at91_adc.c
> > +++ b/drivers/iio/adc/at91_adc.c
> > @@ -248,12 +248,14 @@ static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
> >  	struct iio_poll_func *pf = p;
> >  	struct iio_dev *idev = pf->indio_dev;
> >  	struct at91_adc_state *st = iio_priv(idev);
> > +	struct iio_chan_spec const *chan;
> >  	int i, j = 0;
> >  
> >  	for (i = 0; i < idev->masklength; i++) {
> >  		if (!test_bit(i, idev->active_scan_mask))
> >  			continue;
> > -		st->buffer[j] = at91_adc_readl(st, AT91_ADC_CHAN(st, i));
> > +		chan = idev->channels + i;
> > +		st->buffer[j] = at91_adc_readl(st, AT91_ADC_CHAN(st, chan->channel));
> >  		j++;
> >  	}
> >  
> > -- 
> > 2.7.4
> >   

Re: [PATCH v2 1/2] iio: adc: at91: fix acking DRDY irq on simple conversions

[Jonathan Cameron]

On Mon, 24 Sep 2018 10:51:43 +0300
Eugen Hristev <eugen.hristev@microchip.com> wrote:

> When doing simple conversions, the driver did not acknowledge the DRDY irq.
> If this irq status is not acked, it will be left pending, and as soon as a
> trigger is enabled, the irq handler will be called, it doesn't know why
> this status has occurred because no channel is pending, and then it will go
> int a irq loop and board will hang.
> To avoid this situation, read the LCDR after a raw conversion is done.
> 
> Fixes 0e589d5fb ("ARM: AT91: IIO: Add AT91 ADC driver.")
> Cc: Maxime Ripard <maxime.ripard@bootlin.com>
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
> ---
> Hello Jonathan,
> 
> I moved this LCDR read/acknowledge into the IRQ handler after the conversion
> value is being read.
Ah.. This all makes more sense now. I'd misunderstood originally and thought
we were looking at a read raw that wasn't using the interrupt at all.

Sorry about that.

However, mostly by coincidence (given I misread the code) I think
this is a neater way to do this than the previous option as it
puts it near the actual read.

Given Maxime is the author of this one though I'd like to leave it
on the list a little longer before applying.

At this stage in the cycle I'll probably just queue it up for the
next merge window anyway (marked for stable). It's not exactly a new bug
after all.

Thanks,

Jonathan
> Sorry about the noise to stable@vger, removed from message.
> 
> Thanks,
> Eugen
> 
>  drivers/iio/adc/at91_adc.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
> index 44b5168..e3be88e 100644
> --- a/drivers/iio/adc/at91_adc.c
> +++ b/drivers/iio/adc/at91_adc.c
> @@ -279,6 +279,8 @@ static void handle_adc_eoc_trigger(int irq, struct iio_dev *idev)
>  		iio_trigger_poll(idev->trig);
>  	} else {
>  		st->last_value = at91_adc_readl(st, AT91_ADC_CHAN(st, st->chnb));
> +		/* Needed to ACK the DRDY interruption */
> +		at91_adc_readl(st, AT91_ADC_LCDR);
>  		st->done = true;
>  		wake_up_interruptible(&st->wq_data_avail);
>  	}

Re: [PATCH v2 1/2] iio: adc: at91: fix acking DRDY irq on simple conversions

[Ludovic Desroches]

On Mon, Sep 24, 2018 at 10:51:43AM +0300, Eugen Hristev wrote:
> When doing simple conversions, the driver did not acknowledge the DRDY irq.
> If this irq status is not acked, it will be left pending, and as soon as a
> trigger is enabled, the irq handler will be called, it doesn't know why
> this status has occurred because no channel is pending, and then it will go
> int a irq loop and board will hang.
> To avoid this situation, read the LCDR after a raw conversion is done.
> 
> Fixes 0e589d5fb ("ARM: AT91: IIO: Add AT91 ADC driver.")
> Cc: Maxime Ripard <maxime.ripard@bootlin.com>
> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com> 

> ---
> Hello Jonathan,
> 
> I moved this LCDR read/acknowledge into the IRQ handler after the conversion
> value is being read.
> Sorry about the noise to stable@vger, removed from message.
> 
> Thanks,
> Eugen
> 
>  drivers/iio/adc/at91_adc.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
> index 44b5168..e3be88e 100644
> --- a/drivers/iio/adc/at91_adc.c
> +++ b/drivers/iio/adc/at91_adc.c
> @@ -279,6 +279,8 @@ static void handle_adc_eoc_trigger(int irq, struct iio_dev *idev)
>  		iio_trigger_poll(idev->trig);
>  	} else {
>  		st->last_value = at91_adc_readl(st, AT91_ADC_CHAN(st, st->chnb));
> +		/* Needed to ACK the DRDY interruption */
> +		at91_adc_readl(st, AT91_ADC_LCDR);
>  		st->done = true;
>  		wake_up_interruptible(&st->wq_data_avail);
>  	}
> -- 
> 2.7.4
> 

Re: [PATCH v2 1/2] iio: adc: at91: fix acking DRDY irq on simple conversions

[Jonathan Cameron]

On Tue, 25 Sep 2018 15:17:39 +0200
Ludovic Desroches <ludovic.desroches@microchip.com> wrote:

> On Mon, Sep 24, 2018 at 10:51:43AM +0300, Eugen Hristev wrote:
> > When doing simple conversions, the driver did not acknowledge the DRDY irq.
> > If this irq status is not acked, it will be left pending, and as soon as a
> > trigger is enabled, the irq handler will be called, it doesn't know why
> > this status has occurred because no channel is pending, and then it will go
> > int a irq loop and board will hang.
> > To avoid this situation, read the LCDR after a raw conversion is done.
> > 
> > Fixes 0e589d5fb ("ARM: AT91: IIO: Add AT91 ADC driver.")
> > Cc: Maxime Ripard <maxime.ripard@bootlin.com>
> > Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>  
> Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com> 
Applied to the togreg branch of iio.git and marked for stable.

It's been broken long enough that I think it can wait for the merge window
coming in a few weeks time.

Thanks,

Jonathan

> 
> > ---
> > Hello Jonathan,
> > 
> > I moved this LCDR read/acknowledge into the IRQ handler after the conversion
> > value is being read.
> > Sorry about the noise to stable@vger, removed from message.
> > 
> > Thanks,
> > Eugen
> > 
> >  drivers/iio/adc/at91_adc.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
> > index 44b5168..e3be88e 100644
> > --- a/drivers/iio/adc/at91_adc.c
> > +++ b/drivers/iio/adc/at91_adc.c
> > @@ -279,6 +279,8 @@ static void handle_adc_eoc_trigger(int irq, struct iio_dev *idev)
> >  		iio_trigger_poll(idev->trig);
> >  	} else {
> >  		st->last_value = at91_adc_readl(st, AT91_ADC_CHAN(st, st->chnb));
> > +		/* Needed to ACK the DRDY interruption */
> > +		at91_adc_readl(st, AT91_ADC_LCDR);
> >  		st->done = true;
> >  		wake_up_interruptible(&st->wq_data_avail);
> >  	}
> > -- 
> > 2.7.4
> >