Re: [PATCH v2 3/3] iio: adc: at91-sama5d2_adc: update for other trigger usage

Eugen.Hristev
2020-01-20T07:24:55Z

On 17.01.2020 19:42, Jonathan Cameron wrote:

> On Mon, 13 Jan 2020 12:07:10 +0000
> <Eugen.Hristev@microchip.com> wrote:
>
>> From: Eugen Hristev <eugen.hristev@microchip.com>
>>
>> This change will allow the at91-sama5d2_adc driver to use other triggers
>> than it's own.
>> In particular, tested with the sysfs trigger.
>> To be able to achieve this functionality, some changes were required:
>> 1) Do not enable/disable channels when enabling/disabling the trigger.
>> This is because the trigger is enabled/disabled only for our trigger
>> (obviously). We need channels enabled/disabled regardless of what trigger is
>> being used.
>> 2) Cope with DMA : DMA cannot be used when using another type of trigger.
>> Other triggers work through pollfunc, so we get polled anyway on every trigger.
>> Thus we have to obtain data at every trigger.
>> 3) When to start conversion? The usual pollfunc (store time from subsystem)
>> would be in hard irq and this would be a good way, but current iio subsystem
>> recommends to have it in the threaded irq. Thus adding software start
>> code in this handler.
>> 4) Buffer config: we need to setup buffer regardless of our own device's
>> trigger. We may get one attached later.
>> 5) IRQ handling: we use our own device IRQ only if it's our own trigger
>> and we do not use DMA . If we use DMA, we use the DMA controller's IRQ.
>>
>> Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
>
> +CC Alexandru as he's doing a lot of cleanup around the buffer functions.
> I'd like Alex to take a look at this.
>
> A few comments inline from me.
>
> Thanks,
>
> Jonathan
>
>
>
>> ---
>> Changes in v2:
>> - adapt to the situation of having the previous two patches ahead in the series
>>
>> drivers/iio/adc/at91-sama5d2_adc.c | 140 +++++++++++++++++++------------------
>> 1 file changed, 73 insertions(+), 67 deletions(-)
>>
>> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
>> index 454a493..34df043 100644
>> --- a/drivers/iio/adc/at91-sama5d2_adc.c
>> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
>> @@ -728,7 +728,6 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
>> struct iio_dev *indio = iio_trigger_get_drvdata(trig);
>> struct at91_adc_state *st = iio_priv(indio);
>> u32 status = at91_adc_readl(st, AT91_SAMA5D2_TRGR);
>> - u8 bit;
>>
>> /* clear TRGMOD */
>> status &= ~AT91_SAMA5D2_TRGR_TRGMOD_MASK;
>> @@ -739,45 +738,6 @@ static int at91_adc_configure_trigger(struct iio_trigger *trig, bool state)
>> /* set/unset hw trigger */
>> at91_adc_writel(st, AT91_SAMA5D2_TRGR, status);
>>
>> - for_each_set_bit(bit, indio->active_scan_mask, indio->num_channels) {
>> - struct iio_chan_spec const *chan = at91_adc_chan_get(indio, bit);
>> - u32 cor;
>> -
>> - if (!chan)
>> - continue;
>> - /* these channel types cannot be handled by this trigger */
>> - if (chan->type == IIO_POSITIONRELATIVE ||
>> - chan->type == IIO_PRESSURE)
>> - continue;
>> -
>> - if (state) {
>> - cor = at91_adc_readl(st, AT91_SAMA5D2_COR);
>> -
>> - if (chan->differential)
>> - cor |= (BIT(chan->channel) |
>> - BIT(chan->channel2)) <<
>> - AT91_SAMA5D2_COR_DIFF_OFFSET;
>> - else
>> - cor &= ~(BIT(chan->channel) <<
>> - AT91_SAMA5D2_COR_DIFF_OFFSET);
>> -
>> - at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
>> - }
>> -
>> - if (state)
>> - at91_adc_writel(st, AT91_SAMA5D2_CHER,
>> - BIT(chan->channel));
>> - else
>> - at91_adc_writel(st, AT91_SAMA5D2_CHDR,
>> - BIT(chan->channel));
>> - }
>> - /* enable irq only if not using DMA */
>> - if (state && !st->dma_st.dma_chan)
>> - at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_DRDY);
>> - /* disable irq only if not using DMA */
>> - if (!state && !st->dma_st.dma_chan)
>> - at91_adc_writel(st, AT91_SAMA5D2_IDR, AT91_SAMA5D2_IER_DRDY);
>> -
>> return 0;
>> }
>>
>> @@ -901,9 +861,22 @@ static int at91_adc_dma_start(struct iio_dev *indio_dev)
>> return 0;
>> }
>>
>> +static bool at91_adc_buffer_check_use_irq(struct iio_dev *indio,
>> + struct at91_adc_state *st)
>> +{
>> + /* if using DMA, we do not use our own IRQ (we use DMA-controller) */
>> + if (st->dma_st.dma_chan)
>> + return false;
>> + /* if the trigger is not ours, then it has its own IRQ */
>> + if (iio_trigger_validate_own_device(indio->trig, indio))
>> + return false;
>> + return true;
>> +}
>> +
>> static int at91_adc_buffer_postenable(struct iio_dev *indio_dev)
>> {
>> int ret;
>> + u8 bit;
>> struct at91_adc_state *st = iio_priv(indio_dev);
>>
>> /* check if we are enabling triggered buffer or the touchscreen */
>> @@ -921,9 +894,40 @@ static int at91_adc_buffer_postenable(struct iio_dev *indio_dev)
>> ret = at91_adc_dma_start(indio_dev);
>> if (ret) {
>> dev_err(&indio_dev->dev, "buffer postenable failed\n");
>> + iio_triggered_buffer_predisable(indio_dev);
>
> This seems odd given you have called the iio_triggered_buffer_postenable yet..
> That is below.

Hi Jonathan,

You are right, I will remove this.

>
>> return ret;
>> }
>>
>> + for_each_set_bit(bit, indio_dev->active_scan_mask,
>> + indio_dev->num_channels) {
>> + struct iio_chan_spec const *chan =
>> + at91_adc_chan_get(indio_dev, bit);
>> + u32 cor;
>> +
>> + if (!chan)
>> + continue;
>> + /* these channel types cannot be handled by this trigger */
>> + if (chan->type == IIO_POSITIONRELATIVE ||
>> + chan->type == IIO_PRESSURE)
>> + continue;
>> +
>> + cor = at91_adc_readl(st, AT91_SAMA5D2_COR);
>> +
>> + if (chan->differential)
>> + cor |= (BIT(chan->channel) | BIT(chan->channel2)) <<
>> + AT91_SAMA5D2_COR_DIFF_OFFSET;
>> + else
>> + cor &= ~(BIT(chan->channel) <<
>> + AT91_SAMA5D2_COR_DIFF_OFFSET);
>> +
>> + at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
>> +
>> + at91_adc_writel(st, AT91_SAMA5D2_CHER, BIT(chan->channel));
>> + }
>> +
>> + if (at91_adc_buffer_check_use_irq(indio_dev, st))
>> + at91_adc_writel(st, AT91_SAMA5D2_IER, AT91_SAMA5D2_IER_DRDY);
>> +
>> return iio_triggered_buffer_postenable(indio_dev);
>> }
>>
>> @@ -944,21 +948,11 @@ static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
>> if (!(indio_dev->currentmode & INDIO_ALL_TRIGGERED_MODES))
>> return -EINVAL;
>>
>> - /* continue with the triggered buffer */
>> - ret = iio_triggered_buffer_predisable(indio_dev);
>> - if (ret < 0)
>> - dev_err(&indio_dev->dev, "buffer predisable failed\n");
>> -
>> - if (!st->dma_st.dma_chan)
>> - return ret;
>> -
>> - /* if we are using DMA we must clear registers and end DMA */
>> - dmaengine_terminate_sync(st->dma_st.dma_chan);
>> -
>> /*
>> - * For each enabled channel we must read the last converted value
>> + * For each enable channel we must disable it in hardware.
>> + * In the case of DMA, we must read the last converted value
>> * to clear EOC status and not get a possible interrupt later.
>> - * This value is being read by DMA from LCDR anyway
>> + * This value is being read by DMA from LCDR anyway, so it's not lost.
>> */
>> for_each_set_bit(bit, indio_dev->active_scan_mask,
>> indio_dev->num_channels) {
>> @@ -971,12 +965,28 @@ static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
>> if (chan->type == IIO_POSITIONRELATIVE ||
>> chan->type == IIO_PRESSURE)
>> continue;
>> +
>> + at91_adc_writel(st, AT91_SAMA5D2_CHDR, BIT(chan->channel));
>> +
>> if (st->dma_st.dma_chan)
>> at91_adc_readl(st, chan->address);
>> }
>>
>> + if (at91_adc_buffer_check_use_irq(indio_dev, st))
>> + at91_adc_writel(st, AT91_SAMA5D2_IDR, AT91_SAMA5D2_IER_DRDY);
>> +
>> /* read overflow register to clear possible overflow status */
>> at91_adc_readl(st, AT91_SAMA5D2_OVER);
>> +
>> + /* continue with the triggered buffer */
>> + ret = iio_triggered_buffer_predisable(indio_dev);
>> + if (ret < 0)
>> + dev_err(&indio_dev->dev, "buffer predisable failed\n");
>> +
>> + /* if we are using DMA we must clear registers and end DMA */
>> + if (st->dma_st.dma_chan)
>> + dmaengine_terminate_sync(st->dma_st.dma_chan);
>
> This ordering is going to stop Alex doing his rework to remove the need
> to manually call iio_triggered_buffer_predisable. Why does it make
> sense to do the dma stuff after that?
>
> Ah I see it always did and the postenable is the opposite of what Alex
> has been moving to as well.

Ok, so keep it like this ?

>
>> +
>> return ret;
>> }
>>
>> @@ -1131,6 +1141,13 @@ static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
>> struct iio_dev *indio_dev = pf->indio_dev;
>> struct at91_adc_state *st = iio_priv(indio_dev);
>>
>> + /*
>> + * If it's not our trigger, start a conversion now, as we are
>> + * actually polling the trigger now.
>> + */
>> + if (iio_trigger_validate_own_device(indio_dev->trig, indio_dev))
>> + at91_adc_writel(st, AT91_SAMA5D2_CR, AT91_SAMA5D2_CR_START);
>> +
>> if (st->dma_st.dma_chan)
>> at91_adc_trigger_handler_dma(indio_dev);
>> else
>> @@ -1143,20 +1160,9 @@ static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
>>
>> static int at91_adc_buffer_init(struct iio_dev *indio)
>> {
>> - struct at91_adc_state *st = iio_priv(indio);
>> -
>> - if (st->selected_trig->hw_trig) {
>> - return devm_iio_triggered_buffer_setup(&indio->dev, indio,
>> - &iio_pollfunc_store_time,
>> - &at91_adc_trigger_handler, &at91_buffer_setup_ops);
>> - }
>> - /*
>> - * we need to prepare the buffer ops in case we will get
>> - * another buffer attached (like a callback buffer for the touchscreen)
>> - */
>> - indio->setup_ops = &at91_buffer_setup_ops;
>> -
>> - return 0;
>> + return devm_iio_triggered_buffer_setup(&indio->dev, indio,
>> + &iio_pollfunc_store_time,
>> + &at91_adc_trigger_handler, &at91_buffer_setup_ops);
>> }
>>
>> static unsigned at91_adc_startup_time(unsigned startup_time_min,
>
>
>