2009-06-21 20:32:49 Minimum size for I/O memory region (as requested by request_mem_region)?

Jay Ku (UNITED STATES)

Message: 76096

I'm putting logic for several different devices in an FPGA. These will be accessed by different device drivers, and I assume each driver needs to call request_mem_region before accessing registers in memory-mapped I/O space. Is there a minimum size (in bytes) that request_mem_region can allocate? All of my memory-mapped registers will be in a single async memory bank (AMSx), and I'm limited in how many address bits I can bring into the FPGA. It looks like I'll have a single block of 32 consecutive words that will be split up into 3 or 4 unequal regions (i.e. 16 + 10 + 4 + 2 words). Will it be a problem to allocate these small blocks of memory to different drivers?

Thanks,

Jay

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2009-06-21 20:55:04 Re: Minimum size for I/O memory region (as requested by request_mem_region)?

Mike Frysinger (UNITED STATES)

Message: 76097

using request_mem_region isnt strictly required, but it does prevent drivers from conflicting. i dont believe there is any size limit on the request.