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tx dmac backpressure

Question asked by zutta1 on Feb 24, 2017
Latest reply on Mar 3, 2017 by zutta1


i use four tx dmacs with axi streaming IF for transfering data bursts with ~2MB/s average data rate to a fifo (based on zed board with fmcomms1). All four data streams ar asynchronous and each start of the stream should be triggered individually by a signal in the PL. At the software side i am using for each stream an instance of libiio/ad9361-iiostream.c at master · analogdevicesinc/libiio · GitHub  which is reading from a file, the buffer size is 7200 words.


At the moment it works fine as long as i assigning m_axis_ready immediately after starting the tx thread. But if i wait some seconds from starting the tx thread to assigning m_axis_ready the transfer hangs and the fifo does not reach its watermark.


I already added a iio_context_set_timeout(ctx,10000) to the tx software, but it does not help.


Do you have an idea what could be wrong?

Thanks a lot for your help!