linux-kernel - Re: [PATCH v5 07/15] iio: sx9310: Use long instead of int for channel bitmaps

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Date:   Thu, 6 Aug 2020 19:30:57 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Daniel Campello <campello@...omium.org>
Cc:     LKML <devicetree@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Stephen Boyd <swboyd@...omium.org>,
        Douglas Anderson <dianders@...omium.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        linux-iio@...r.kernel.org
Subject: Re: [PATCH v5 07/15] iio: sx9310: Use long instead of int for
 channel bitmaps

On Mon,  3 Aug 2020 17:58:07 -0600
Daniel Campello <campello@...omium.org> wrote:

> Uses for_each_set_bit() macro to loop over channel bitmaps.
> 
> Signed-off-by: Daniel Campello <campello@...omium.org>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
> Reviewed-by: Stephen Boyd <swboyd@...omium.org>
Applied,

Thanks,

Jonathan

> ---
> 
> Changes in v5: None
> Changes in v4: None
> Changes in v3:
>  - Added static assert for number of channels.
> 
> Changes in v2:
>  - Changed prox_stat to chan_prox_stat bitmap.
> 
>  drivers/iio/proximity/sx9310.c | 39 ++++++++++++++++++----------------
>  1 file changed, 21 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/iio/proximity/sx9310.c b/drivers/iio/proximity/sx9310.c
> index 127b1ba79e2dea..f78500b8a5841e 100644
> --- a/drivers/iio/proximity/sx9310.c
> +++ b/drivers/iio/proximity/sx9310.c
> @@ -119,6 +119,7 @@
>  
>  /* 4 hardware channels, as defined in STAT0: COMB, CS2, CS1 and CS0. */
>  #define SX9310_NUM_CHANNELS				4
> +static_assert(SX9310_NUM_CHANNELS < BITS_PER_LONG);
>  
>  struct sx9310_data {
>  	/* Serialize access to registers and channel configuration */
> @@ -130,7 +131,7 @@ struct sx9310_data {
>  	 * Last reading of the proximity status for each channel.
>  	 * We only send an event to user space when this changes.
>  	 */
> -	bool prox_stat[SX9310_NUM_CHANNELS];
> +	unsigned long chan_prox_stat;
>  	bool trigger_enabled;
>  	/* Ensure correct alignment of timestamp when present. */
>  	struct {
> @@ -140,7 +141,8 @@ struct sx9310_data {
>  	/* Remember enabled channels and sample rate during suspend. */
>  	unsigned int suspend_ctrl0;
>  	struct completion completion;
> -	unsigned int chan_read, chan_event;
> +	unsigned long chan_read;
> +	unsigned long chan_event;
>  	int channel_users[SX9310_NUM_CHANNELS];
>  	unsigned int whoami;
>  };
> @@ -283,15 +285,16 @@ static const struct regmap_config sx9310_regmap_config = {
>  };
>  
>  static int sx9310_update_chan_en(struct sx9310_data *data,
> -				 unsigned int chan_read,
> -				 unsigned int chan_event)
> +				 unsigned long chan_read,
> +				 unsigned long chan_event)
>  {
>  	int ret;
> +	unsigned long channels = chan_read | chan_event;
>  
> -	if ((data->chan_read | data->chan_event) != (chan_read | chan_event)) {
> +	if ((data->chan_read | data->chan_event) != channels) {
>  		ret = regmap_update_bits(data->regmap, SX9310_REG_PROX_CTRL0,
>  					 SX9310_REG_PROX_CTRL0_SENSOREN_MASK,
> -					 chan_read | chan_event);
> +					 channels);
>  		if (ret)
>  			return ret;
>  	}
> @@ -532,6 +535,7 @@ static void sx9310_push_events(struct iio_dev *indio_dev)
>  	unsigned int val, chan;
>  	struct sx9310_data *data = iio_priv(indio_dev);
>  	s64 timestamp = iio_get_time_ns(indio_dev);
> +	unsigned long prox_changed;
>  
>  	/* Read proximity state on all channels */
>  	ret = regmap_read(data->regmap, SX9310_REG_STAT0, &val);
> @@ -540,24 +544,23 @@ static void sx9310_push_events(struct iio_dev *indio_dev)
>  		return;
>  	}
>  
> -	for (chan = 0; chan < SX9310_NUM_CHANNELS; chan++) {
> +	/*
> +	 * Only iterate over channels with changes on proximity status that have
> +	 * events enabled.
> +	 */
> +	prox_changed = (data->chan_prox_stat ^ val) & data->chan_event;
> +
> +	for_each_set_bit(chan, &prox_changed, SX9310_NUM_CHANNELS) {
>  		int dir;
>  		u64 ev;
> -		bool new_prox = val & BIT(chan);
> -
> -		if (!(data->chan_event & BIT(chan)))
> -			continue;
> -		if (new_prox == data->prox_stat[chan])
> -			/* No change on this channel. */
> -			continue;
>  
> -		dir = new_prox ? IIO_EV_DIR_FALLING : IIO_EV_DIR_RISING;
> +		dir = val & BIT(chan) ? IIO_EV_DIR_FALLING : IIO_EV_DIR_RISING;
>  		ev = IIO_UNMOD_EVENT_CODE(IIO_PROXIMITY, chan,
>  					  IIO_EV_TYPE_THRESH, dir);
>  
>  		iio_push_event(indio_dev, ev, timestamp);
> -		data->prox_stat[chan] = new_prox;
>  	}
> +	data->chan_prox_stat = val;
>  }
>  
>  static irqreturn_t sx9310_irq_thread_handler(int irq, void *private)
> @@ -714,13 +717,13 @@ static irqreturn_t sx9310_trigger_handler(int irq, void *private)
>  static int sx9310_buffer_preenable(struct iio_dev *indio_dev)
>  {
>  	struct sx9310_data *data = iio_priv(indio_dev);
> -	unsigned int channels = 0;
> +	unsigned long channels = 0;
>  	int bit, ret;
>  
>  	mutex_lock(&data->mutex);
>  	for_each_set_bit(bit, indio_dev->active_scan_mask,
>  			 indio_dev->masklength)
> -		channels |= BIT(indio_dev->channels[bit].channel);
> +		__set_bit(indio_dev->channels[bit].channel, &channels);
>  
>  	ret = sx9310_update_chan_en(data, channels, data->chan_event);
>  	mutex_unlock(&data->mutex);