RE: [BUG] Suspend failure with nbcon + pm_debug_messages (Linux 6.18-rc4)

[John Ogness]

On 2025-11-04, Sherry Sun <sherry.sun@xxxxxxx> wrote:
>> Thanks for reporting! I believe this is the same issue reported by NVIDIA [0]
>> when we tried to switch the 8250 UART driver to nbcon.
>>
>> We have been working with NVIDIA recently to address the issue. There is a
>> patch [1] we are currently testing that looks good so far. It is based on 6.17
>> but should work fine for 6.18-rc4 as well. Can you give it a spin?
>
> Thanks a lot for your quick reply, I just tried the patch [1] on my
> i.MX8MP EVK with L6.18-rc4, it does fix the suspend issue.  Now i.MX
> UART nbcon can enter suspend with `pm_debug_messages` is turned on.
> May I know what is the upstream plan for the patch [1]?

Thanks for confirming the fix. I will make an official post on LKML with
the patch today. Since the i.MX nbcon-driver is already mainline, I will
CC stable. I will CC you as well.

Note that the patch still needs a formal review from the printk folks
once it hits LKML.

John Ogness

>> [1] https://github.com/Linutronix/linux/commit/ae173249d9028ef159fba040bdab260d80dda43f