[alsa-devel] [PATCH v3 07/11] IIO: consumer: allow to set buffer sizes

[Jonathan Cameron]

On 20/03/17 11:30, Arnaud Pouliquen wrote:
> 
> 
> On 03/19/2017 11:44 PM, Jonathan Cameron wrote:
>> On 17/03/17 14:08, Arnaud Pouliquen wrote:
>>> Add iio consumer API to set buffer size and watermark according
>>> to sysfs API.
>>>
>>> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen at st.com>
>> Hmm. Not keen on the length one.  Setting a requested watermark
>> is fair enough.  There is no actually buffer in these cases though
>> so setting it's length is downright odd..
> Length and watermark are configurable from user land through sysfs.
> Seems to me logic to also propose it in inkern API...
> But I can clean length , no problem.
The concept of length for the consumer interface doesn't currently
make sense as it refers to an actual buffer.   The consumer interface
currently passes one entry at a time...
> 
>>
>> Guess this is part of the hacks we need to clean up by doing
>> the dma buffer consumer stuff right...
> Yes all is linked :-).
> 
>>
>> Jonathan
>>> ---
>>>  drivers/iio/buffer/industrialio-buffer-cb.c | 12 ++++++++++++
>>>  include/linux/iio/consumer.h                | 13 +++++++++++++
>>>  2 files changed, 25 insertions(+)
>>>
>>> diff --git a/drivers/iio/buffer/industrialio-buffer-cb.c b/drivers/iio/buffer/industrialio-buffer-cb.c
>>> index b8f550e..43c066a 100644
>>> --- a/drivers/iio/buffer/industrialio-buffer-cb.c
>>> +++ b/drivers/iio/buffer/industrialio-buffer-cb.c
>>> @@ -103,6 +103,18 @@ struct iio_cb_buffer *iio_channel_get_all_cb(struct device *dev,
>>>  }
>>>  EXPORT_SYMBOL_GPL(iio_channel_get_all_cb);
>>>  
>>> +int iio_channel_cb_set_buffer_params(struct iio_cb_buffer *cb_buff,
>>> +				      size_t length, size_t watermark)
>>> +{
>>> +	if (!length || length < watermark)
>>> +		return -EINVAL;
>>> +	cb_buff->buffer.watermark = watermark;
>>> +	cb_buff->buffer.length = length;
>>> +
>>> +	return 0;
>>> +}
>>> +EXPORT_SYMBOL_GPL(iio_channel_start_all_cb);
>>> +
>>>  int iio_channel_start_all_cb(struct iio_cb_buffer *cb_buff)
>>>  {
>>>  	return iio_update_buffers(cb_buff->indio_dev, &cb_buff->buffer,
>>> diff --git a/include/linux/iio/consumer.h b/include/linux/iio/consumer.h
>>> index cb44771..0f6e94d 100644
>>> --- a/include/linux/iio/consumer.h
>>> +++ b/include/linux/iio/consumer.h
>>> @@ -134,6 +134,19 @@ struct iio_cb_buffer *iio_channel_get_all_cb(struct device *dev,
>>>  						       void *private),
>>>  					     void *private);
>>>  /**
>>> + * iio_channel_cb_set_buffer_size() - set the buffer length.
>>> + * @cb_buffer:		The callback buffer from whom we want the channel
>>> + *			information.
>>> + * @length: buffer length in bytes
>>> + * @watermark: buffer watermark in bytes
>>> + *
>>> + * This function allows to configure the buffer length. The watermark if
>>> + * forced to half of the buffer.
>>> + */
>>> +int iio_channel_cb_set_buffer_params(struct iio_cb_buffer *cb_buffer,
>>> +				     size_t length, size_t watermark);
>>> +
>>> +/**
>>>   * iio_channel_release_all_cb() - release and unregister the callback.
>>>   * @cb_buffer:		The callback buffer that was allocated.
>>>   */
>>>
>>
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