On 9/4/25 4:04 PM, Boris Brezillon wrote:
Hello Boris,
I suspect the extra soft reset I did before "un-halted" the GPU and
allowed it to proceed.
Hm, not quite. I mean, you still need to explicitly boot the MCU after
a reset, which is what the write to MCU_CONTROL [1] does. What the
soft-reset does though, is reset all GPU blocks, including the MCU.
This means the MCU starts from a fresh state when you reach [1].
I have a feeling the write to MCU_CONTROL does nothing in my case.
I believe it does, otherwise you wouldn't be able to kick the MCU
and get things working until the first runtime suspend happens. I gut
feeling is that there's something fishy in the FW or SoC integration
that causes the FW HALT request to put the MCU/GPU in a bad state
preventing further MCU_CONTROL(AUTO_START) from functioning correctly
after that point.
I wonder who at NXP could chime in ... Peng, do you know ?
Is there some way to probe the MCU state before/after setting GLB_HALT,
and also before/after the MCU_CONTROL write, using
gpu_read()/gpu_write() register operations, to find out what is going on
with the MCU at each point ?
Yes, there's an MCU_STATUS register [1].
Is that the only register I can use , or is there something more
detailed ? This register only returns values 0..3 which is not very
informative.
