Re: [PATCH] serial: qcom-geni: keep registered console runtime active

[David Heidelberg]

On 19/08/2026 18:46, Konrad Dybcio wrote:
> From: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>
>
> Commit aee1f94dab13 ("serial: qcom-geni: remove .pm callback, use
> runtime PM in startup/shutdown") moved runtime PM references from the
> serial-core PM callback to the port startup and shutdown callbacks.
>
> The serial core used to leave the console port powered after
> registration, but after the callback was removed the temporary probe
> reference is always released. Console writes are not tied to an open TTY
> and can run from contexts which cannot resume the device, so a
> runtime-suspended console can stall. This was observed on a Qualcomm
> X1E80100 CRD device, as the boot console became flakey across boots.
>
> Acquire a runtime PM reference when the console is set up and release it
> through the console exit callback. This keeps the device active only
> while the console is registered and balances the reference when the
> console is disabled or re-enabled through sysfs.
>
> Fixes: aee1f94dab13 ("serial: qcom-geni: remove .pm callback, use runtime PM in startup/shutdown")
> Assisted-by: LLM
> Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxxxxxxxx>
> ---
>   drivers/tty/serial/qcom_geni_serial.c | 26 ++++++++++++++++++++++++--
>   1 file changed, 24 insertions(+), 2 deletions(-)
This also fixes a regression on sdm845: since v7.3-rc1 (or on next-20260820), 
OnePlus 6 and 6T crash into the Qualcomm crash dump mode on every s2idle suspend 
attempt (no kernel output, warm reset via PS_HOLD with the TZ download cookie 
set, no panic in ramoops).

Tested-by: David Heidelberg <david@xxxxxxx> # OnePlus 6T (sdm845)

One thing this leaves open: with the console holding a single reference,
pm_runtime_force_suspend() goes through pm_runtime_need_not_resume() and
pm_runtime_force_resume() does not power the port back up, so
uart_resume_port() programs the termios and resumes the console on a
powered-down port; it only comes back through startup() if the tty was
open. I'll send a patch on top for that.

Thank you
David