Re: [PATCH v2 07/14] iio: sx9310: Use long instead of int for channel bitmaps

From: Stephen Boyd <swboyd@chromium.org>
To: Daniel Campello <campello@chromium.org>,
	LKML <devicetree@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Cc: Jonathan Cameron <jic23@kernel.org>,
	Daniel Campello <campello@chromium.org>,
	Andy Shevchenko <andy.shevchenko@gmail.com>,
	Douglas Anderson <dianders@chromium.org>,
	Enrico Granata <egranata@chromium.org>,
	Hartmut Knaack <knaack.h@gmx.de>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
	linux-iio@vger.kernel.org
Subject: Re: [PATCH v2 07/14] iio: sx9310: Use long instead of int for channel bitmaps
Date: Tue, 28 Jul 2020 18:03:32 -0700	[thread overview]
Message-ID: <159598461271.1360974.15436404116157938506@swboyd.mtv.corp.google.com> (raw)
In-Reply-To: <20200728170317.v2.7.Iecaa50e469918a385b3e5dab375e442540ea2ad4@changeid>

Quoting Daniel Campello (2020-07-28 16:05:13)
> Uses for_each_set_bit() macro to loop over channel bitmaps.
> 
> Signed-off-by: Daniel Campello <campello@chromium.org>
> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
> ---
> 
> Changes in v2:
>  - Changed prox_stat to chan_prox_stat bitmap.
> 
>  drivers/iio/proximity/sx9310.c | 38 ++++++++++++++++++----------------
>  1 file changed, 20 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/iio/proximity/sx9310.c b/drivers/iio/proximity/sx9310.c
> index 75e85dcd6b3572..1f04ab8507ec62 100644
> --- a/drivers/iio/proximity/sx9310.c
> +++ b/drivers/iio/proximity/sx9310.c
> @@ -130,14 +130,15 @@ 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;

This can be DECLARE_BITMAP(chan_prox_stat, SX9310_NUM_CHANNELS)

>         bool trigger_enabled;
>         /* 64-bit data + 64-bit timestamp buffer */
>         __be16 buffer[SX9310_NUM_CHANNELS + 4] __aligned(8);
>         /* 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;

Same for these?

>         int channel_users[SX9310_NUM_CHANNELS];
>         unsigned int whoami;
>  };
> @@ -280,15 +281,16 @@ 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;
>         }
> @@ -531,6 +533,7 @@ 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);
> @@ -539,24 +542,23 @@ 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;

I was expecting:

	bitmap_xor(&prox_changed, &data->chan_prox_stat, &val, SX9310_NUM_CHANNELS);
	bitmap_and(&prox_changed, &data->chan_event, SX9310_NUM_CHANNELS);

> +
> +       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)
> @@ -713,13 +715,13 @@ 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;

Use DECLARE_BITMAP(channels, SX9310_NUM_CHANNELS)?

>         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);