Pcie is blocking XO shutdown

[divyverm-cmd]

On some devices where modem is not present, PCIe6 instance is causing sync state to fail resulting in MAX voting at ICC. This results in preventing XO shutdown to happen.

[krishnachaitanya-linux]

On Glymur, PCIe6 is intended for modem attach and its initialization is dependent on UEFI. On targets where the modem is not connected, UEFI does not enable PCIe6, resulting in the PCIe link remaining down. As a result, the PCIe driver probe fails in HLOS and the corresponding interconnect (ICC) sync_state callback is never invoked. Since sync_state is not reached, the default max bandwidth votes applied during boot are not released, causing the ICC path to remain at MAX and preventing XO shutdown, leading to the observed power impact. This behavior is expected on Glymur compute targets when no endpoint (modem) is present due to the dependency on UEFI-based PCIe initialization. Usually, PCIe would be disabled via CDT when the modem is absent, but with upstream constraints now supporting only a single CDT configuration, dynamically disabling PCIe based on modem presence is no longer feasible. A separate DTSI configuration based on CDT state was also evaluated, but is not practical under the same limitation. As a result, the final decision is to disable the modem-related PCIe instance by default and enable it only through the corresponding overlay when modem support is required.

[krishnachaitanya-linux]

Raised a PR for this now, #1390