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Date:   Sun, 26 Apr 2020 11:22:50 +0100
From:   Jonathan Cameron <jic23@kernel.org>
To:     Alexandru Ardelean <alexandru.ardelean@analog.com>
Cc:     <linux-iio@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <lars@metafoo.de>
Subject: Re: [RFC PATCH 1/4] iio: Move scan mask management to the core
Message-ID: <20200426112250.36bb8c6b@archlinux>
In-Reply-To: <20200426104538.657a2d9a@archlinux>
References: <20200424051818.6408-1-alexandru.ardelean@analog.com>
        <20200424051818.6408-2-alexandru.ardelean@analog.com>
        <20200426104538.657a2d9a@archlinux>
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On Sun, 26 Apr 2020 10:45:38 +0100
Jonathan Cameron <jic23@kernel.org> wrote:

> On Fri, 24 Apr 2020 08:18:15 +0300
> Alexandru Ardelean <alexandru.ardelean@analog.com> wrote:
> 
> > From: Lars-Peter Clausen <lars@metafoo.de>
> > 
> > Let the core handle the buffer scan mask management including allocation
> > and channel selection. Having this handled in a central place rather than
> > open-coding it all over the place will make it easier to change the
> > implementation.
> > 
> > Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
> > Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>  
> 
> Hi Alex,
> 
> For some reason I only have patch 1 of this series of 4.
Ah. My email went crazy. Rest of series now turned up from somewhere :)

Thanks,

J

> 
> This one looks reasonable to me as abstracts away how it is implemented
> which is good. A few comments and a question inline.
> 
> Jonathan
> 
> 
> > ---
> >  drivers/iio/buffer/industrialio-buffer-cb.c | 17 ++++------
> >  drivers/iio/industrialio-buffer.c           | 36 +++++++++++++++------
> >  drivers/iio/inkern.c                        | 15 +++++++++
> >  include/linux/iio/consumer.h                | 10 ++++++
> >  4 files changed, 58 insertions(+), 20 deletions(-)
> > 
> > diff --git a/drivers/iio/buffer/industrialio-buffer-cb.c b/drivers/iio/buffer/industrialio-buffer-cb.c
> > index 47c96f7f4976..b50f1f48cac6 100644
> > --- a/drivers/iio/buffer/industrialio-buffer-cb.c
> > +++ b/drivers/iio/buffer/industrialio-buffer-cb.c
> > @@ -33,8 +33,7 @@ static int iio_buffer_cb_store_to(struct iio_buffer *buffer, const void *data)
> >  static void iio_buffer_cb_release(struct iio_buffer *buffer)
> >  {
> >  	struct iio_cb_buffer *cb_buff = buffer_to_cb_buffer(buffer);
> > -
> > -	bitmap_free(cb_buff->buffer.scan_mask);
> > +	iio_buffer_free_scanmask(buffer);
> >  	kfree(cb_buff);
> >  }
> >  
> > @@ -72,27 +71,25 @@ struct iio_cb_buffer *iio_channel_get_all_cb(struct device *dev,
> >  	}
> >  
> >  	cb_buff->indio_dev = cb_buff->channels[0].indio_dev;
> > -	cb_buff->buffer.scan_mask = bitmap_zalloc(cb_buff->indio_dev->masklength,
> > -						  GFP_KERNEL);
> > -	if (cb_buff->buffer.scan_mask == NULL) {
> > -		ret = -ENOMEM;
> > +
> > +	ret = iio_buffer_alloc_scanmask(&cb_buff->buffer, cb_buff->indio_dev);
> > +	if (ret)
> >  		goto error_release_channels;
> > -	}
> > +
> >  	chan = &cb_buff->channels[0];
> >  	while (chan->indio_dev) {
> >  		if (chan->indio_dev != cb_buff->indio_dev) {
> >  			ret = -EINVAL;
> >  			goto error_free_scan_mask;
> >  		}
> > -		set_bit(chan->channel->scan_index,
> > -			cb_buff->buffer.scan_mask);
> > +		iio_buffer_channel_enable(&cb_buff->buffer, chan);
> >  		chan++;
> >  	}
> >  
> >  	return cb_buff;
> >  
> >  error_free_scan_mask:
> > -	bitmap_free(cb_buff->buffer.scan_mask);
> > +	iio_buffer_free_scanmask(&cb_buff->buffer);
> >  error_release_channels:
> >  	iio_channel_release_all(cb_buff->channels);
> >  error_free_cb_buff:
> > diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
> > index 221157136af6..c06691281287 100644
> > --- a/drivers/iio/industrialio-buffer.c
> > +++ b/drivers/iio/industrialio-buffer.c
> > @@ -206,6 +206,26 @@ void iio_buffer_init(struct iio_buffer *buffer)
> >  }
> >  EXPORT_SYMBOL(iio_buffer_init);
> >  
> > +int iio_buffer_alloc_scanmask(struct iio_buffer *buffer,
> > +			      struct iio_dev *indio_dev)  
> I'm not sure passing the indio_dev in here makes sense as it
> obscures that all we are getting from it is the masklength.
> May be better to pass that explicitly.
> 
> > +{
> > +	if (!indio_dev->masklength)
> > +		return 0;  
> 
> This is a bit of an oddity of the old code.  Any idea why we
> allow things to continue with a masklength of 0?  Seems to me
> that it is thoroughly broken if that occurs!
> 
> > +
> > +	buffer->scan_mask = bitmap_zalloc(indio_dev->masklength, GFP_KERNEL);
> > +	if (buffer->scan_mask == NULL)
> > +		return -ENOMEM;
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(iio_buffer_alloc_scanmask);
> > +
> > +void iio_buffer_free_scanmask(struct iio_buffer *buffer)
> > +{
> > +	bitmap_free(buffer->scan_mask);
> > +}
> > +EXPORT_SYMBOL_GPL(iio_buffer_free_scanmask);
> > +
> >  /**
> >   * iio_buffer_set_attrs - Set buffer specific attributes
> >   * @buffer: The buffer for which we are setting attributes
> > @@ -1301,14 +1321,10 @@ int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
> >  				indio_dev->scan_index_timestamp =
> >  					channels[i].scan_index;
> >  		}
> > -		if (indio_dev->masklength && buffer->scan_mask == NULL) {
> > -			buffer->scan_mask = bitmap_zalloc(indio_dev->masklength,
> > -							  GFP_KERNEL);
> > -			if (buffer->scan_mask == NULL) {
> > -				ret = -ENOMEM;
> > -				goto error_cleanup_dynamic;
> > -			}
> > -		}
> > +
> > +		ret = iio_buffer_alloc_scanmask(buffer, indio_dev);
> > +		if (ret)
> > +			goto error_cleanup_dynamic;
> >  	}
> >  
> >  	buffer->scan_el_group.name = iio_scan_elements_group_name;
> > @@ -1329,7 +1345,7 @@ int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
> >  	return 0;
> >  
> >  error_free_scan_mask:
> > -	bitmap_free(buffer->scan_mask);
> > +	iio_buffer_free_scanmask(buffer);
> >  error_cleanup_dynamic:
> >  	iio_free_chan_devattr_list(&buffer->scan_el_dev_attr_list);
> >  	kfree(indio_dev->buffer->buffer_group.attrs);
> > @@ -1342,7 +1358,7 @@ void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev)
> >  	if (!indio_dev->buffer)
> >  		return;
> >  
> > -	bitmap_free(indio_dev->buffer->scan_mask);
> > +	iio_buffer_free_scanmask(indio_dev->buffer);
> >  	kfree(indio_dev->buffer->buffer_group.attrs);
> >  	kfree(indio_dev->buffer->scan_el_group.attrs);
> >  	iio_free_chan_devattr_list(&indio_dev->buffer->scan_el_dev_attr_list);
> > diff --git a/drivers/iio/inkern.c b/drivers/iio/inkern.c
> > index ede99e0d5371..f35cb9985edc 100644
> > --- a/drivers/iio/inkern.c
> > +++ b/drivers/iio/inkern.c
> > @@ -11,6 +11,7 @@
> >  
> >  #include <linux/iio/iio.h>
> >  #include "iio_core.h"
> > +#include <linux/iio/buffer_impl.h>
> >  #include <linux/iio/machine.h>
> >  #include <linux/iio/driver.h>
> >  #include <linux/iio/consumer.h>
> > @@ -857,6 +858,20 @@ int iio_write_channel_raw(struct iio_channel *chan, int val)
> >  }
> >  EXPORT_SYMBOL_GPL(iio_write_channel_raw);
> >  
> > +void iio_buffer_channel_enable(struct iio_buffer *buffer,
> > +			       const struct iio_channel *chan)
> > +{
> > +	set_bit(chan->channel->scan_index, buffer->scan_mask);
> > +}
> > +EXPORT_SYMBOL_GPL(iio_buffer_channel_enable);
> > +
> > +void iio_buffer_channel_disable(struct iio_buffer *buffer,
> > +				const struct iio_channel *chan)
> > +{
> > +	clear_bit(chan->channel->scan_index, buffer->scan_mask);
> > +}
> > +EXPORT_SYMBOL_GPL(iio_buffer_channel_disable);
> > +
> >  unsigned int iio_get_channel_ext_info_count(struct iio_channel *chan)
> >  {
> >  	const struct iio_chan_spec_ext_info *ext_info;
> > diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
> > index c4118dcb8e05..dbc87c26250a 100644
> > --- a/include/linux/iio/consumer.h
> > +++ b/include/linux/iio/consumer.h
> > @@ -12,6 +12,7 @@
> >  
> >  struct iio_dev;
> >  struct iio_chan_spec;
> > +struct iio_buffer;
> >  struct device;
> >  
> >  /**
> > @@ -342,6 +343,15 @@ int iio_read_channel_scale(struct iio_channel *chan, int *val,
> >  int iio_convert_raw_to_processed(struct iio_channel *chan, int raw,
> >  	int *processed, unsigned int scale);
> >  
> > +void iio_buffer_channel_enable(struct iio_buffer *buffer,
> > +			       const struct iio_channel *chan);
> > +void iio_buffer_channel_disable(struct iio_buffer *buffer,
> > +				const struct iio_channel *chan);
> > +
> > +int iio_buffer_alloc_scanmask(struct iio_buffer *buffer,
> > +			      struct iio_dev *indio_dev);
> > +void iio_buffer_free_scanmask(struct iio_buffer *buffer);
> > +
> >  /**
> >   * iio_get_channel_ext_info_count() - get number of ext_info attributes
> >   *				      connected to the channel.  
>