lowRISC / lowRISC/opentitan

[top_darjeeling,clkmgr] Clock Measurement is wrong for Darjeeling

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Component:Darjeeling
Dominant language
SystemVerilog
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Description

Darjeeling runs at 1000/250/62.5 MHz. The clkmgr has inbuild measurement primitives. These are however still configured for the Earlgrey frequencies (96/48/24 MHz) like following example shows. (Cnt = 480)

https://github.com/lowRISC/opentitan/blob/e65178ab2dfdd5da7e33d1e56fe759d15dec1fc0/hw/top_darjeeling/ip/clkmgr/rtl/autogen/clkmgr.sv#L602-L623

/cc @neeraj-rv @andreaskurth

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with hw/top_darjeeling/ip/clkmgr/rtl/autogen/clkmgr.sv at lines 602-623 and inspect how the clock measurement primitives are configured. Compare those Earlgrey values with Darjeeling's 1000/250/62.5 MHz frequencies. Done means Darjeeling's measurement configuration uses the correct frequencies instead of the values shown in the issue.

Written by the indexing model from the issue text.

Assessment

Domain
embedded-iot
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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