The hci_suspend_notifier which was introduced last year, is causing problems for uart attached btrtl devices. These devices may loose their firmware and their baudrate setting over a suspend/resume. Since we don't even know the baudrate after a suspend/resume recovering from this is tricky. The driver solves this by treating these devices the same as USB BT HCIs which drop of the bus during suspend. Specifically the driver: 1. Simply unconditionally turns the device fully off during system-suspend to save maximum power. 2. Calls device_reprobe() from a workqueue to fully re-init the device from scratch on system-resume (unregistering the old HCI and registering a new HCI). This means that these devices do not benefit from the suspend / resume handling work done by the hci_suspend_notifier. At best this unnecessarily adds some time to the suspend/resume time. But in practice this is actually causing problems: 1. These btrtl devices seem to not like the HCI_OP_WRITE_SCAN_ENABLE( SCAN_DISABLED) request being send to them when entering the BT_SUSPEND_CONFIGURE_WAKE state. The same request send on BT_SUSPEND_DISCONNECT works fine, but the second one send (unnecessarily?) from the BT_SUSPEND_CONFIGURE_WAKE transition causes the device to hang: [ 573.497754] PM: suspend entry (s2idle) [ 573.554615] Filesystems sync: 0.056 seconds [ 575.837753] Bluetooth: hci0: Timed out waiting for suspend events [ 575.837801] Bluetooth: hci0: Suspend timeout bit: 4 [ 575.837925] Bluetooth: hci0: Suspend notifier action (3) failed: -110 2. The PM_POST_SUSPEND / BT_RUNNING transition races with the driver-unbinding done by the device_reprobe() work. If the hci_suspend_notifier wins the race it is talking to a dead device leading to the following errors being logged: [ 598.686060] Bluetooth: hci0: Timed out waiting for suspend events [ 598.686124] Bluetooth: hci0: Suspend timeout bit: 5 [ 598.686237] Bluetooth: hci0: Suspend notifier action (4) failed: -110 In both cases things still work, but the suspend-notifier is causing these ugly errors getting logged and ut increase both the suspend- and the resume-time by 2 seconds. This commit works around these problems by disabling (unregistering) the hci_suspend_notifier. Note that any eventual hci_unregister_dev() will call unregister_pm_notifier() a second time, this is fine it will simply fail with -ENOENT and hci_unregister_dev() ignores the return value. Cc: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx> Cc: Vasily Khoruzhick <anarsoul@xxxxxxxxx> Cc: Abhishek Pandit-Subedi <abhishekpandit@xxxxxxxxxxxx> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx> --- drivers/bluetooth/hci_h5.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/bluetooth/hci_h5.c b/drivers/bluetooth/hci_h5.c index 7be16a7f653b..acbcc676d6c2 100644 --- a/drivers/bluetooth/hci_h5.c +++ b/drivers/bluetooth/hci_h5.c @@ -14,6 +14,7 @@ #include <linux/of_device.h> #include <linux/serdev.h> #include <linux/skbuff.h> +#include <linux/suspend.h> #include <net/bluetooth/bluetooth.h> #include <net/bluetooth/hci_core.h> @@ -876,6 +877,13 @@ static int h5_btrtl_setup(struct h5 *h5) bool flow_control; int err; + /* + * Since h5_btrtl_resume() does a device_reprobe() the suspend handling + * done by the hci_suspend_notifier is not necessary; it actually causes + * delays and a bunch of errors to get logged, so disable it. + */ + unregister_pm_notifier(&h5->hu->hdev->suspend_notifier); + btrtl_dev = btrtl_initialize(h5->hu->hdev, h5->id); if (IS_ERR(btrtl_dev)) return PTR_ERR(btrtl_dev); -- 2.29.2
