On 12/12/14 11:08, Jonathan Cameron wrote:
> On 26/11/14 17:55, Lars-Peter Clausen wrote:
>> If a buffer implementation does not implement the set_length() callback the
>> length will be static and can not be changed by userspace. Mark the length
>> attribute as a read only property in this case so userspace is aware of this
>> rather than just silently accepting any length value.
>>
>> Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>
> Nice little change.
>
Having said that I doubt that longterm this will apply to many devices
as we'll be routing more and more hardware buffers through a software
front end and that front end will be variable size...
Anyhow, applied to the togreg branch of iio.git with fuzz etc
from my earlier patch tweaking.
> Thanks
> Jonathan
>> ---
>> drivers/iio/industrialio-buffer.c | 10 +++++++---
>> 1 file changed, 7 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/iio/industrialio-buffer.c b/drivers/iio/industrialio-buffer.c
>> index a4d3ff6..3e0c3a9 100644
>> --- a/drivers/iio/industrialio-buffer.c
>> +++ b/drivers/iio/industrialio-buffer.c
>> @@ -416,8 +416,7 @@ static ssize_t iio_buffer_write_length(struct device *dev,
>> if (iio_buffer_is_active(indio_dev->buffer)) {
>> ret = -EBUSY;
>> } else {
>> - if (buffer->access->set_length)
>> - buffer->access->set_length(buffer, val);
>> + buffer->access->set_length(buffer, val);
>> ret = 0;
>> }
>> mutex_unlock(&indio_dev->mlock);
>> @@ -755,6 +754,8 @@ static const char * const iio_scan_elements_group_name = "scan_elements";
>>
>> static DEVICE_ATTR(length, S_IRUGO | S_IWUSR, iio_buffer_read_length,
>> iio_buffer_write_length);
>> +static struct device_attribute dev_attr_length_ro = __ATTR(length,
>> + S_IRUGO, iio_buffer_read_length, NULL);
>> static DEVICE_ATTR(enable, S_IRUGO | S_IWUSR,
>> iio_buffer_show_enable, iio_buffer_store_enable);
>>
>> @@ -781,7 +782,10 @@ int iio_buffer_alloc_sysfs(struct iio_dev *indio_dev)
>> if (!buffer->buffer_group.attrs)
>> return -ENOMEM;
>>
>> - buffer->buffer_group.attrs[0] = &dev_attr_length.attr;
>> + if (buffer->access->set_length)
>> + buffer->buffer_group.attrs[0] = &dev_attr_length.attr;
>> + else
>> + buffer->buffer_group.attrs[0] = &dev_attr_length_ro.attr;
>> buffer->buffer_group.attrs[1] = &dev_attr_enable.attr;
>> if (buffer->attrs)
>> memcpy(&buffer->buffer_group.attrs[2], buffer->attrs,
>>
>
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