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>
> ---
> Changes in v2:
> - Use the new HCI_QUIRK_NO_SUSPEND_NOTIFIER quirk, instead of directly
> unregistering the notifier from hci_h5.c
> ---
> drivers/bluetooth/hci_h5.c | 7 +++++++
> drivers/bluetooth/hci_serdev.c | 3 +++
> drivers/bluetooth/hci_uart.h | 13 +++++++------
> 3 files changed, 17 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/bluetooth/hci_h5.c b/drivers/bluetooth/hci_h5.c
> index 7be16a7f653b..e8f3afab6587 100644
> --- a/drivers/bluetooth/hci_h5.c
> +++ b/drivers/bluetooth/hci_h5.c
> @@ -914,6 +914,13 @@ static int h5_btrtl_setup(struct h5 *h5)
>
> static void h5_btrtl_open(struct h5 *h5)
> {
> + /*
> + * 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.
> + */
> + set_bit(HCI_UART_NO_SUSPEND_NOTIFIER, &h5->hu->hdev_flags);
I'm not sure we should enable this for all RTL devices rather than
based on the specific project. RTL8822C will also be using hci_h5 but
intends to support wake on bt (meaning it shouldn't be losing firmware
around suspend).
+ Max Chou: You are proposing a change to add project id to btrtl.
Should we use that instead to set this quirk for 8723 devices (and
others which lose fw around suspend)?
(https://patchwork.kernel.org/project/bluetooth/patch/20210127030152.3940-1-max.chou@xxxxxxxxxxx/)
> +
> /* Devices always start with these fixed parameters */
> serdev_device_set_flow_control(h5->hu->serdev, false);
> serdev_device_set_parity(h5->hu->serdev, SERDEV_PARITY_EVEN);
> diff --git a/drivers/bluetooth/hci_serdev.c b/drivers/bluetooth/hci_serdev.c
> index ef96ad06fa54..dbc14b8ac477 100644
> --- a/drivers/bluetooth/hci_serdev.c
> +++ b/drivers/bluetooth/hci_serdev.c
> @@ -349,6 +349,9 @@ int hci_uart_register_device(struct hci_uart *hu,
> if (test_bit(HCI_UART_EXT_CONFIG, &hu->hdev_flags))
> set_bit(HCI_QUIRK_EXTERNAL_CONFIG, &hdev->quirks);
>
> + if (test_bit(HCI_UART_NO_SUSPEND_NOTIFIER, &hu->hdev_flags))
> + set_bit(HCI_QUIRK_NO_SUSPEND_NOTIFIER, &hdev->quirks);
> +
> if (test_bit(HCI_UART_CREATE_AMP, &hu->hdev_flags))
> hdev->dev_type = HCI_AMP;
> else
> diff --git a/drivers/bluetooth/hci_uart.h b/drivers/bluetooth/hci_uart.h
> index 4e039d7a16f8..4df2330ac103 100644
> --- a/drivers/bluetooth/hci_uart.h
> +++ b/drivers/bluetooth/hci_uart.h
> @@ -35,12 +35,13 @@
> #define HCI_UART_NOKIA 10
> #define HCI_UART_MRVL 11
>
> -#define HCI_UART_RAW_DEVICE 0
> -#define HCI_UART_RESET_ON_INIT 1
> -#define HCI_UART_CREATE_AMP 2
> -#define HCI_UART_INIT_PENDING 3
> -#define HCI_UART_EXT_CONFIG 4
> -#define HCI_UART_VND_DETECT 5
> +#define HCI_UART_RAW_DEVICE 0
> +#define HCI_UART_RESET_ON_INIT 1
> +#define HCI_UART_CREATE_AMP 2
> +#define HCI_UART_INIT_PENDING 3
> +#define HCI_UART_EXT_CONFIG 4
> +#define HCI_UART_VND_DETECT 5
> +#define HCI_UART_NO_SUSPEND_NOTIFIER 6
>
> struct hci_uart;
> struct serdev_device;
> --
> 2.29.2
>
