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

[Abel Vesa]

On 26-08-19 18:46:47, 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>

Reviewed-by: Abel Vesa <abel.vesa@xxxxxxxxxxxxxxxx>