search

enjoy-digital / litex

Build your hardware, easily!
Other
2.89k stars 555 forks source link

No longer get a .we read strobe when a CSRStatus is read if using the picorv32 soft cpu #2040

Closed dwalton65 closed 4 weeks ago

dwalton65 commented 1 month ago

This was working previously. Yesterday I updated litex, and since then I no longer get a .we read strobe when a CSRStatus is read. I am using the picorv32 soft cpu. If I change to the vexriscv soft cpu, then the .we read strobe works again.

I need to use the picorv32 soft cpu, as I have been unable to get litex working when using the vexriscv soft cpu and the diamond toolchain. I need to use the diamond toolchain, as I have been unable to get IDDR71B primitives working with the trellis toolchain.

test3.gz "test3.gz" contains a project to test the .we read strobe. This is built by running ./litex_build

If I enter cntr on the litex_term, I get the following: picorv32:

rdata = 0xaa
re_cntr = 0
we_cntr = 0
wdata_cntr = 2

vexriscv:

rdata = 0xaa
re_cntr = 0
we_cntr = 1
wdata_cntr = 2

we_cntr remains 0 when using the picorv32.

picorv32: litescope and gtkwave showing the point where I expect a .we strobe. main_tst_rdata_we remains low. picorv32

vexriscv: .we strobe (main_tst_rdata_we) is as expected. vexriscv

dwalton65 commented 1 month ago

I reverted to the previous version of the files csr_bus.py, ahb.py and wishbone.py

git checkout dde9605 -- litex/soc/interconnect/csr_bus.py
git checkout b19d992 -- litex/soc/interconnect/ahb.py
git checkout fbf03ec -- litex/soc/interconnect/wishbone.py

Now if I enter cntr on the litex_term, I get the following: picorv32:

rdata = 0xaa
re_cntr = 0
we_cntr = 1
wdata_cntr = 2

"we_cntr = 1" shows the .we read strobe has been seen.

picorv32: .we strobe (main_tst_rdata_we) is as expected again. picorv32_reverted

dwalton65 commented 1 month ago

Accidentally closed, so reopened.

m-byte commented 1 month ago

This sounds like it might have been caused by #1999. It also broke the etherbone crossover UART.

enjoy-digital commented 1 month ago

Hi @dwalton65,

as pointed by @m-byte, this is probably caused by #1999 that changed CSR access behavior that was previously masking some Wishbone sel issues on Wishbone Masters. This should be fixed with https://github.com/enjoy-digital/litex/commit/afc66fd5cfd048c5881c4d0ae0ce008874ee99f8, can you try it?

dwalton65 commented 4 weeks ago

Hi @dwalton65,

as pointed by @m-byte, this is probably caused by #1999 that changed CSR access behavior that was previously masking some Wishbone sel issues on Wishbone Masters. This should be fixed with afc66fd, can you try it?

The .we read strobe when a CSRStatus is read appears to be working again. I tested 6d0ae25

enjoy-digital commented 4 weeks ago

Great, thanks @m-byte for the feedback.