ad7991 with odc - Unable to create buffer


I am using the ad7991 adc with the Raspberry Pi2.

Reading single values from the \iio:device0\in_voltage0_raw works fine, but when trying to stream the data with osc, I am getting errors "Error while reading data: Resource temporarily unavailable". My host pc is lubuntu 14.04.

from the output of iio_info I see it cannot read some of the the attributes (add_trigger, raw, etc), even running with sudo.

I have connected the iio-trig-sysfs by "echo sysfstrig1 > current_trigger". Maybe this is not the right trigger to use... but thought using it for testing purposes only.

loading the hrtimer trigger by "sudo modprobe iio-trig-hrtimer" didnt actually created the trigger as i hoped it do.. for this i tried adding the following code in my bcm2709.c board file (found on this forum):

static const char *hrtimer_trigger_pdata[] = {  
     "0", /* 0 is the name of the trigger */  
static struct platform_device hrtimer_trigger = {  
     .name = "iio_hrtimer_trigger",  
     .dev = {  
          .platform_data = &hrtimer_trigger_pdata,  

and registering the device with:


still didnt show up the hrtimer0 iio device..

can somebody point me in the right direction what causes this problem and why the hrtimer trigger dont show up?