Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
11 years ago

ACP port under Linux

Hi, Is there any trick to using the ACP port from FPGA under Linux (3.9)? I'm setting the f2h AR & AW CACHE/PROT/USER by hand, post-qsys, but don't see any indication that the SCU cares at all...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
10 years ago

--- Quote Start ---

I have configures the AXI port attributes as you said and also sending to the HDL module the physical address | 0x80000000, but I am getting a kernel panic after starting writing to that memory location, did you configure something for the ACP port before using it?

--- Quote End ---

Does it work without "| 0x80000000"? That bypasses the cache so needs non-cached memory (pgprot_noncached) but should work correctly. If you get kernel panic on both, it has to be a driver typo/issue. If it only happens on ACP, I don't know. The AXI port attributes were the only thing I needed to change for ACP, no software changes were needed other than the flag.