<david-sawatzke[m>
Hi, I've done something with the dram on the colorlite and it doesn't work. Is there any way to simulate Litedram stuff with migen? DRAMMemory sounds promising, but seems to be for internal tests only
<_florent_>
somlo: the SDCard is now also working with Linux-on-LiteX-Vexriscv, that was the clock-frequency that was missing in the .dts as you suggested by mail, thanks!
<_florent_>
somlo: I forgot to add it to VexRiscv-SMP when replacing VexRiscv with VexRiscv-SMP in litex_json2dts.py
<somlo>
_florent_: that's great news!
<somlo>
_florent_: now what's left is to figure out why multi-block transfers are having such a hard time
<somlo>
I may end up having to learn something new (debug running gateware) after all... Been successfully avoiding it all this time, but the writing is on the proverbial wall :D
<_florent_>
somlo: yes that's great. The fact that we are now using a common linux branch is a time saver for finding these subtle things :)
<somlo>
speaking of, what's the purpose of the "loop" and "offset" registers in the LiteX DMA modules?
<somlo>
seems "loop" resets the FSM while it's running, but I'm probably misunderstanding that - anywhere I can go read about it?
<_florent_>
somlo: also, what do you think about adding Rocket support to litex_json2dts? This would simplify Linux-on-LiteX-Rocket and would also mutualize the efforts on the .dts front
<somlo>
_florent_: that's next on my agenda after getting to the bottom of the linux-vs-litesdcard issue
<_florent_>
somlo: as we already discussed by mail, LiteScope can also be very powerful to develop/debug Linux drivers! You should really try it :)
<somlo>
_florent_: I'll drop everything and do that, starting today (modulo how much crap $DAYJOB will throw my way) :D
<somlo>
it seems if one writes to it during the DMA transfer, it starts again from the beginning -- does that make sense, am I right, and if not, what's going on :)
<somlo>
am I even in the proverbial ballpark with my understanding of how this is supposed to work ?
<_florent_>
somlo: in LiteX's DMA: loop CSRStorage allow you to create a continous DMA that restart automatically when done
<_florent_>
somlo: the offset can be used to monitor the DMA status (to know how much data have been already transfered)
<_florent_>
ah sorry, haven't seen your previous messages, so you are right yes
<_florent_>
no sure you'll have a need for the loop mode, but the offset can be useful in case you have troubles with a DMA that does not end
<somlo>
_florent_: thanks! any clue on why only the DMAReader exposes `offset` as a read-only CSR (and not DMAWriter as well)?
<_florent_>
somlo: I probably only had a need for it on the DMAReader, but we could add it to the Writer too
<somlo>
_florent_: ok, I don't know that we need it (yet), was just curious if there's some underlying structural reason why it could only work on *Writer :)
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<chgavilana>
hi: I am trying to use an hdmi output with litevideo. Can anyone who has experience with litevideo give me the reference of the monitor you used?
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<cr1901_modern>
_florent_: I had a bad day computer-wise yesterday. I'll test your PR changes soon.
<somlo>
anyone in possession of a nexys-a7 board able to (or willing to try) building linux-on-litex-rocket bitstream using the nexys4ddr instructions? (https://github.com/litex-hub/linux-on-litex-rocket)
<somlo>
I have a report that programming the bitstream on a nexys-a7 results in only the led-chaser but no console output, and I only have the "classic" nexys4ddr, so I'm blind to any small-but-relevant differences between it and the nexys-a7
<daveshah>
it doesn't respond to input beyond that point
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<somlo>
daveshah: thanks!
<somlo>
that's more than what I got in the bug report (led-chaser, no other console output)
<daveshah>
sorry, I've just realised that I'm an idiot and I actually have an old nexys4
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<daveshah>
I thought it was an A7 for some reason but it's actually a nexys4ddr
<somlo>
works fine on my old nexys4 (and iirc. it passed timing in vivado)
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<somlo>
daveshah: depending on how fresh your (litex-hub/linux litex-rebase branch) kernel is, the hanging microsd driver may or may not be reason for concern... :)
<somlo>
but thanks for checking, sorry to have wasted your time on the old board
<daveshah>
Don't worry, it was my own confusion to blame!
<Dolu>
fpu
<Dolu>
sorear : Got some FPU design which pass add/mul/fma/div/sqrt
<Dolu>
So basicaly, the design choices are : To not implement subnormals, having 1 mul pipeline + 1 add pipeline, which are chained when FMA, both div and sqrt use a LUT based initial aproximation and get closer via 2-3 newton iterations.
<Dolu>
Currently trying to have a centralised register file between multiple CPU, just not sure how well this will scale for floating point store, as it has to do the roundtripe between CPU instruction decode => FPU register file => CPU D$
<_florent_>
somlo: I thought the nexys4ddr and nexysa7 where exactly the same but it seems not. If the led chaser is on, the clock is probably good and the boards is not in reset
<_florent_>
the UART pins are the same, so the CPU should start printing things on the UART
<_florent_>
Unfortunately I also only have a nexys4ddr
<somlo>
_florent_: that's what I remember from reading about the nexys a7 too, but no actual first hand experience...
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<somlo>
_florent_, daveshah: apparently after some tinkering with jumpers, my nexys-a7 user managed to get some console output when booting their bitstream, so we're back on assuming the a7 is backward compatible :) Thanks again for your help!
<somlo>
* back *to* assuming... Apparently I need more coffee...
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<cr1901_modern>
_florent_: Your changes work fine
<cr1901_modern>
re: litex_term
<zyp>
_florent_, do you know if the vexriscv interrupt controller is documented anywhere?