FPGA Bridge enabled, but signal tap shows data is zeros

[Altera_Forum]

Thanks in Advanced. 

 Previously I have done the same thing on a Macnica Sodia board but used the FPGA DDR memory to do the same thing -- so I HAVE VERIFIED that my firmware works as advertised. Currently - I want to use HPS DDR to reduce the DDR chips needed for our custom PCB so ... I am   working on a Macnica Helio board took the Q14.1 Golden Design and added my IPs then - I have used Q17.1 bsp-editor and associated commands to generate the u-boot and preloader.  If necessary I can provide those instructions.  I am using kernel 4.1.33-ltsi with some extra features enabled.   At first my *.dtb file was not correctly resetting the bridge, but subsequently I changed the *.dtb (and from another post I matched it to the *.dtb of the kernel).  AND I can see during boot [ 2.272449] fpga_manager fpga0: Altera SOCFPGA FPGA Manager registered [ 2.279599] altera_hps2fpga_bridge sopc@0:fpgabridge@0: fpga bridge [hps2fpga] registered [ 2.288011] altera_hps2fpga_bridge sopc@0:fpgabridge@1: fpga bridge [lwhps2fpga] registered [ 2.296481] altera_hps2fpga_bridge sopc@0:fpgabridge@2: fpga bridge [fpga2hps] registered   And I can see everything in /sys/class/fpga-bridge/   I HAVE SIGNAL TAP SET UP TO SEE THE avs and avm signals --> I have a device driver that has a kernel buffer of known data and I give the firmware that start address to read from BUT I can see all the correct bus signals but the data read from the address IS NOT THE EXPECTED DATA IT IS ZERO !!!   What am I missing?   IS MY KERNEL NOT IN SYNC??  Also, how do I know the address of fpgabridge@0, @1, @2 - to verify that they match properly (it used to be at boot you saw the actual addresses).  Any help/ideas will be greatly appreciated !!!

[Altera_Forum]

SOLVED !!!!! 

 I switched my allocation of the memory buffers to:   static char * dmakbuf1; "kbuf" static char * dmakbuf2;  static dma_addr_t handle; static dma_addr_t handle2; static size_t size = (1024 * PAGE_SIZE);    dmakbuf1 = dma_alloc_coherent(NULL, size, &handle, GFP_KERNEL);  if ( dmakbuf1 == NULL ) printk( KERN_ALERT "dma_alloc_coherent FAILED !!!! BUF1 \n" );  dmakbuf2 = dma_alloc_coherent(NULL, size, &handle2, GFP_KERNEL);  if ( dmakbuf2 == NULL ) printk( KERN_ALERT "dma_alloc_coherent FAILED !!!! BUF2 \n" );    THE RETURN VALUES == "handle" the physical address is what I give to the FIRMWARE  and the "dmakbuf" is what the user space code needs (NO ioremap)  Hope this helps someone else.