Re: [PATCH] serial: qcom-geni: add force suspend/resume to system sleep callbacks

[Mukesh Savaliya <mukesh.savaliya@oss.qualcomm.com>]

On 7/1/2026 11:27 AM, Praveen Talari wrote:
> During system sleep the hardware resources (clocks, interconnect) are
> not gated because the runtime-suspend callback is never invoked from
> the system sleep path.  This prevents the platform from reaching its
> lowest idle state.
> 
> The system sleep callbacks qcom_geni_serial_suspend() and
> qcom_geni_serial_resume() rely solely on uart_suspend_port() /
> uart_resume_port() to manage power.  uart_suspend_port() drives the
> UART PM state machine to UART_PM_STATE_OFF, which in turn calls
> pm_runtime_put_sync() and eventually the runtime-suspend callback.
> However, if the runtime-PM usage count is still elevated at the time
> of system sleep (e.g. the port is held active by an open file
> descriptor), the runtime-suspend callback is never invoked and the
> hardware resources (clocks, interconnect) remain enabled across
> suspend, preventing the platform from reaching its lowest idle state.
> 
> Fix this by calling pm_runtime_force_suspend() at the end of
> qcom_geni_serial_suspend() so that the runtime-suspend callback is
> always executed regardless of the usage count, and by calling
> pm_runtime_force_resume() at the start of qcom_geni_serial_resume()
> to restore those resources before uart_resume_port() re-opens the
> port.
> 
> Signed-off-by: Praveen Talari <praveen.talari@oss.qualcomm.com>
> ---
[...]
> @@ -1963,7 +1964,19 @@ static int qcom_geni_serial_suspend(struct device *dev)
>   		geni_icc_set_tag(&port->se, QCOM_ICC_TAG_ACTIVE_ONLY);
>   		geni_icc_set_bw(&port->se);
>   	}
> -	return uart_suspend_port(private_data->drv, uport);
> +
> +	ret = uart_suspend_port(private_data->drv, uport);
> +	if (ret)
> +		return ret;
> +
> +	/*
> +	 * When no_console_suspend is set the console must remain active
> +	 * across system sleep, so skip the force suspend path.
> +	 */
> +	if (uart_console(uport) && !uport->suspended)
> +		return 0;
Rather use console_suspend_enabled and take action to go force suspend.
Here, it sounds opposite, if port is resumed, you don't go to suspend 
within suspend function.
> +
> +	return pm_runtime_force_suspend(dev);
Is this really required ? if  uart_suspend_port() successful, what will 
happen with this ?

>   }
>   
[...]