[PATCH 0/3] hwspinlock: sun6i: Allwinner D1 and T113 support

[Indrek Kruusa]

Hi,

I managed to run this patch series on a Sipeed Lichee RV Dock (Allwinner D1),
in this setup:

  - FreeRTOS on the HiFi4 DSP, running a task that contends for the lock
  - a test kernel module touching the same shared memory, with and without
    taking the lock

The series is applied on top of v7.3-rc7.

What I ran:

  - probe: 3005000.hwlock binds and the driver reports 32 locks

  - mutual exclusion: lock 0, taken alternately by the C906 and the HiFi4.
    Each side added 1 to a shared counter under the lock, 1,000,000 times:

      counter=2000000 expected=2000000 -> EXACT
      tripwire linux=0 dsp=0 -> no overlap

    A tripwire field is set while inside the critical section and read by the
    other side, so overlap is caught independently of the counter.

  - negative control, identical loop with the lock not taken:

      counter=1885761 expected=2000000 -> LOST UPDATES   (5.7% lost)
      tripwire linux=100302 dsp=674915 -> OVERLAP DETECTED

The loss rate in the negative control varies between runs (5-19% observed);
the log linked below is one sample.

Tested-by: Indrek Kruusa <indrek.kruusa at gmail.com>

I put this test setup together with AI assistance. Sources, build
instructions, ready-to-use images (DSP firmware included) for the RV Dock
and for the Nezha (untested), and the captured console logs are here:

  https://github.com/ikruusa/d1-hwspinlock-test

Greetings,
Indrek