[BUG] Rockchip SPI: Runtime PM usage count underflow!

[Vicente Bergas]

On Sun, Aug 18, 2024 at 8:13 PM Vicente Bergas <vicencb at gmail.com> wrote:
>
> Hi,
> i am a user of the CONFIG_SPI_SPIDEV device.
> It stopped working between 6.8 and 6.10.5.
> The SPI bus itself reports no errors to userspace, but no devices
> appear connected to the bus.
> The platform used is RK3328.
> The only spi-related message in dmesg is:
> rockchip-spi ff190000.spi: Runtime PM usage count underflow!
>
> Please, can somebody review this issue?
>
> Regards,
>   Vicente.

I've tried to bisect, but there is some strange behaviour:
The message "Runtime PM usage count underflow!" can also appear on a
good kernel.
In order to have a reasoble iteration speed, i am updating the kernel via kexec.
If a good kernel (6.6.30) is cold-booted, then, all the kernels
kexec'd from it work too.
If a bad kernel (6.10.5) is cold-booted, then a 6.6.30 is kexec'd and
then the same 6.10.5 is kexec'd it becomes a good one.