linux-kernel - Re: [PATCH 15/16] iio: adc: max1027: Support software triggers

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Message-ID: <20210830115046.3727ccc4@jic23-huawei>
Date:   Mon, 30 Aug 2021 11:50:46 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Miquel Raynal <miquel.raynal@...tlin.com>
Cc:     Lars-Peter Clausen <lars@...afoo.de>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        linux-iio@...r.kernel.org, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 15/16] iio: adc: max1027: Support software triggers

On Wed, 18 Aug 2021 13:11:38 +0200
Miquel Raynal <miquel.raynal@...tlin.com> wrote:

> Now that max1027_trigger_handler() has been freed from handling hardware
> triggers EOC situations, we can use it for what it has been designed in
> the first place: trigger software originated conversions.

As mentioned earlier, this is not how I'd normally expect this sort of
case to be handled. I'd be expecting the cnvst trigger to still be calling
this function and the function to do the relevant check to ensure it
knows the data is already available in that case.

> In other
> words, when userspace initiates a conversion with a sysfs trigger or a
> hrtimer trigger, we must do all configuration steps, ie:
> 1- Configuring the trigger
> 2- Configuring the channels to scan
> 3- Starting the conversion (actually done automatically by step 2 in
>    this case)
> 4- Waiting for the conversion to end
> 5- Retrieving the data from the ADC
> 6- Push the data to the IIO core and notify it
> 
> Add the missing steps to this helper and drop the trigger verification
> hook otherwise software triggers would simply not be accepted at all.
> 
> Signed-off-by: Miquel Raynal <miquel.raynal@...tlin.com>
> ---
>  drivers/iio/adc/max1027.c | 26 ++++++++++++++------------
>  1 file changed, 14 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/iio/adc/max1027.c b/drivers/iio/adc/max1027.c
> index 8c5995ae59f2..bb437e43adaf 100644
> --- a/drivers/iio/adc/max1027.c
> +++ b/drivers/iio/adc/max1027.c
> @@ -413,17 +413,6 @@ static int max1027_debugfs_reg_access(struct iio_dev *indio_dev,
>  	return spi_write(st->spi, val, 1);
>  }
>  
> -static int max1027_validate_trigger(struct iio_dev *indio_dev,
> -				    struct iio_trigger *trig)
> -{
> -	struct max1027_state *st = iio_priv(indio_dev);
> -
> -	if (st->trig != trig)
> -		return -EINVAL;
> -
> -	return 0;
> -}
> -
>  static int max1027_set_cnvst_trigger_state(struct iio_trigger *trig, bool state)
>  {
>  	struct iio_dev *indio_dev = iio_trigger_get_drvdata(trig);
> @@ -512,7 +501,21 @@ static irqreturn_t max1027_trigger_handler(int irq, void *private)
>  
>  	pr_debug("%s(irq=%d, private=0x%p)\n", __func__, irq, private);
>  
> +	ret = max1027_configure_trigger(indio_dev);

I'd not expect to see this ever time.  The configuration shouldn't change
from one call of this function to the next.

> +	if (ret)
> +		goto out;
> +
> +	ret = max1027_configure_chans_to_scan(indio_dev);

This should also not change unless it is also responsible for the 'go' signal.
If that's true then it is badly named.

> +	if (ret)
> +		goto out;
> +
> +	ret = max1027_wait_eoc(indio_dev);
> +	if (ret)
> +		goto out;
> +
>  	ret = max1027_read_scan(indio_dev);
> +
> +out:
>  	if (ret)
>  		dev_err(&indio_dev->dev,
>  			"Cannot read scanned values (%d)\n", ret);
> @@ -529,7 +532,6 @@ static const struct iio_trigger_ops max1027_trigger_ops = {
>  
>  static const struct iio_info max1027_info = {
>  	.read_raw = &max1027_read_raw,
> -	.validate_trigger = &max1027_validate_trigger,
>  	.debugfs_reg_access = &max1027_debugfs_reg_access,
>  };
>