Re: serial 00:06: Runtime PM usage count underflow!

[Greg Kroah-Hartman]

On Sat, Nov 16, 2024 at 06:07:27PM +0100, Borislav Petkov wrote:
> Hi folks,
> 
> got a box here which says:
> 
> [    4.654361] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
> [    4.660820] 00:06: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
> [    4.668313] printk: legacy console [ttyS0] disabled
> [    4.676903] serial 00:06: Runtime PM usage count underflow!
> [    4.677175] serial 00:06: disabled
> [    4.677264] serial 00:06: unable to assign resources
> [    4.677356] serial 00:06: probe with driver serial failed with error -16
> [    4.677923] printk: legacy console [ttyS0] disabled
> 
> Any suggestions?

Look in the bios, that seems to be the "old" pnp serial device?  Does it
really have a serial port on the board?  Is it enabled properly?

That is odd, what's the chance that someone didn't enable it in acpi
somehow?

> I'd like to use the serial cable to catch dmesg but somehow the driver doesn't
> like the chip...

It should be the bog-standard 16550 PNP device, check the resource
settings somewhere?  Sorry I can't think of anything else at the
moment...

greg k-h