messages from epiphany -> mailbox are limited. about oh HOT 5 CLOSED

This problem seems to have been introduced in commit ddfeebd - Cleaning up read response logic

from oh.

Updated the test code to use WAIT and can see several places where the access freeze can occur. One has been committed that makes a lot of difference to this issue. #30

from oh.

Well the simulations work ok now, but the latest simulation fix is not good enough to fix the fpga. Still works with simple hello world but as soon as you start to use the mailbox the receive config register gets corrupted, every now an then, with what appears to be contents of the mailbox... odd because this also occurs when not using the interrupt and just polling for messages... about 20% of the time my test runs without any problems and completes without any bus errors and all memory checks seem to work... but about 10% of the time I get the hanging problem and 70% of the time the test runs and you get a bus error. The bus error is best because then you can read the registers with simple memory accesses and each time I see the contents of the mailbox in the config register. When the test hangs there is nothing to do but reboot the board so you loose any logging or chance of investigation.

from oh.

I sorted out the mess in #30 and created a single simple pull request for the fixes so far for this issue. See #32. This new pull request replaces #30 that ended up as a bit of a mess because it was always work in progress!

The comments in the hdl and the commit should explain the fixes. As far as I can tell this is complete and should stop corruption during and after applying wait.... except that somehow my software test of the fpga still results in ERX_CFG getting corrupted about 70% of the time. Now looking else where for corruption and or using the onboard logic analyser to see exactly what is happening in the fpga when corruption occurs!

Here are some test results using #32
testresults160110.txt

from oh.

Just tried out the very latest and it seems like this is now working. I have not tried out all the tests yet but so far so good! Well done!

from oh.