Gidday there, This problem was caused by our custom OPB/PLB bridge not translating correctly from 64-bit access (or bursts) on the PLB to 32-bits on the OPB.
Joshua Lamorie wrote: > Gidday there, > > I have Linux running on a Virtex-II Pro system (with a second FPGA > connected by a custom OPB/PLB bridge). > > I have a device on the OPB bus that I want to provide to applications > through mmap. However, with my current implementation there are some > strange behaviours. > > If I mmap in my application, I can read everything in the device > memory (in blockram and other registers) with no problems. > However if I write only a few bytes, they don't seem to go through to > the memory area, and instead some of the memory is cleared. When I > write a large number of values (e.g. the counter in a for loop). The > values show up, but the first 4 bytes are missing, and it only writes > every other 4 bytes. For example... > > 0000:0000 | 04 05 06 07 00 00 00 00 0c 0d 0e 0f 00 00 00 00 > 0000:0010 | 14 15 16 17 00 00 00 00 1c 1d 1e 1f 00 00 00 00 > > I'm using Rubini's Linux Device Drivers 2nd edition as a reference and > inside the mmap function of my module I simply do > > remap_page_range(vm_start,physical_address, vm_end-vm_start,vm_page_prot) > > I did a quick search through the archives and I noticed that there was > a call io_remap_page_range but that is just a macro pointing to > remap_page_ranger. I also noticed that pgprot_noncached was used in a > 64 bit instance, but that doesn't exist in my kernel. > > I'm using 2.4.26, probably almost a year old now. > > Are there any simple examples of mapping OPB memory to user space? > > I'm also setting a couple of vm_flags such as VM_IO and VM_RESERVED. > Could there be a magic one that I'm missing? I know that there are > some elements of the busses connected to the PPC405 in the Virtex-II > Pro that are 64-bit... is it possible that I'm mapping a 64-bit area > and nothing is correctly written? > > Thanks in advance for any advice. > > Joshua > -- Xiphos Technologies (514) 848-9640 x227 (514) 848-9644 fax www.xiplink.com _______________________________________________ The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. If you have received this in error, please contact the sender and delete this communication and any copy immediately. Thank you.
