From 632d31067be2f414c57955efcf29c79290cc749b Mon Sep 17 00:00:00 2001 From: Pin-yen Lin Date: Fri, 26 Sep 2025 18:23:18 +0800 Subject: PM: sleep: Do not wait on SYNC_STATE_ONLY device links Device links with DL_FLAG_SYNC_STATE_ONLY should not affect system suspend and resume, and functions like device_reorder_to_tail() and device_link_add() don't try to reorder the consumers with that flag. However, dpm_wait_for_consumers() and dpm_wait_for_suppliers() don't check thas flag before triggering dpm_wait(), leading to potential hang during suspend/resume. This can be reproduced on MT8186 Corsola Chromebook with devicetree like: usb-a-connector { compatible = "usb-a-connector"; port { usb_a_con: endpoint { remote-endpoint = <&usb_hs>; }; }; }; usb_host { compatible = "mediatek,mt8186-xhci", "mediatek,mtk-xhci"; port { usb_hs: endpoint { remote-endpoint = <&usb_a_con>; }; }; }; In this case, the two nodes form a cycle and a SYNC_STATE_ONLY devlink between usb_host (supplier) and usb-a-connector (consumer) is created. Address this by exporting device_link_flag_is_sync_state_only() and making dpm_wait_for_consumers() and dpm_wait_for_suppliers() use it when deciding if dpm_wait() should be called. Fixes: 05ef983e0d65a ("driver core: Add device link support for SYNC_STATE_ONLY flag") Signed-off-by: Pin-yen Lin Link: https://patch.msgid.link/20250926102320.4053167-1-treapking@chromium.org [ rjw: Subject and changelog edits ] Signed-off-by: Rafael J. Wysocki --- drivers/base/power/main.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) (limited to 'drivers/base/power/main.c') diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c index e3a7f25bf8d3..c97f8b139dc2 100644 --- a/drivers/base/power/main.c +++ b/drivers/base/power/main.c @@ -278,7 +278,8 @@ static void dpm_wait_for_suppliers(struct device *dev, bool async) * walking. */ dev_for_each_link_to_supplier(link, dev) - if (READ_ONCE(link->status) != DL_STATE_DORMANT) + if (READ_ONCE(link->status) != DL_STATE_DORMANT && + !device_link_flag_is_sync_state_only(link->flags)) dpm_wait(link->supplier, async); device_links_read_unlock(idx); @@ -335,7 +336,8 @@ static void dpm_wait_for_consumers(struct device *dev, bool async) * unregistration). */ dev_for_each_link_to_consumer(link, dev) - if (READ_ONCE(link->status) != DL_STATE_DORMANT) + if (READ_ONCE(link->status) != DL_STATE_DORMANT && + !device_link_flag_is_sync_state_only(link->flags)) dpm_wait(link->consumer, async); device_links_read_unlock(idx); -- cgit v1.2.3