Hi, On Thu, Jan 28, 2021 at 8:34 AM Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > > 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 avoids these problems by disabling the hci_suspend_notifier. > > 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> > --- Per the other conversation thread, since the h5 driver unconditionally reprobes on resume, this change looks good as-is. Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@xxxxxxxxxxxx>
