FROMLIST: serial: qcom-geni: add force suspend/resume to system sleep callbacks - #882
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… callbacks 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. Link: https://lore.kernel.org/all/20260701-add_force_suspend_resume_to_system_sleep_callbacks-v1-1-38c9a721a462@oss.qualcomm.com/ Signed-off-by: Praveen Talari <praveen.talari@oss.qualcomm.com>
vdadhani
requested review from
a team,
Kaushal Kumar (quic-kaushalk),
Shivendra Pratap (quicAspratap) and
Rajendra (rrnayak)
July 31, 2026 06:53
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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.
Link: https://lore.kernel.org/all/20260701-add_force_suspend_resume_to_system_sleep_callbacks-v1-1-38c9a721a462@oss.qualcomm.com/
CRs-Fixed: 4563706