WHY is "txs burstcount" missing in Avalon-MM DMA interface w/ PCIe HIP (Arria 10) ?

[JET60200]

hi all,

we met a performance issue on Arria10 mSGDMA Avalon-MM master(32bit data width) interconnect to PCIE HIP's Avalon-MM (w/ DMA)  slave (txs  32bit).   

For "mSGDMA_writing_to PCIE AVMM(w/ DMA) TXS" operation,  data transfer performance is good.

But for revere "mSGDMA_reading_from PCIE AVMM(w/ DMA) TXS" direction,  data transfer is very slow,  we monitored the "txs waitrequest" signal to de-asserted to activate , found found the reading consumes much more clock cycles (16 x)  than writing operation.  This blocks us for a long time yet. 

I just compare Avalon-MM interface signals between PCIE HIP's "AVMM ( with DMA)" vs PCIE HIP's "AVMM" variant, then we found  the "txs burstcount" signal is missing in  PCIE HIP's "AVMM ( with DMA)" interface , while it really exist in PCIE HIP's "AVMM" interface, as following pic:

   

so my question is :  waht's the reason of this difference ?  Does this "txs burstcount" miss in AVMM-DMA interface would affect the reading (burst) opearion from mSGDMA AValon-MM Master to  PCIE HIP TXS (avalon-mm slave)  ?  

Appreciate helps & advices if any.  Thanks  

[JET60200]

pls kindly reply