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From:   Luiz Augusto von Dentz <luiz.dentz@gmail.com>
Date:   Fri, 28 Aug 2020 10:08:53 -0700
Message-ID: <CABBYNZ+SYSgzR_wX5Cn+5zUjep6HazCdJvAgZ0EE0uLkB_PEGg@mail.gmail.com>
Subject: Re: [Bluez PATCH v2 3/3] policy: Reconnect audio on controller resume
To:     Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
Cc:     Marcel Holtmann <marcel@holtmann.org>,
        ChromeOS Bluetooth Upstreaming 
        <chromeos-bluetooth-upstreaming@chromium.org>,
        "linux-bluetooth@vger.kernel.org" <linux-bluetooth@vger.kernel.org>
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Sender: linux-bluetooth-owner@vger.kernel.org
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Hi Abhishek,

On Thu, Aug 27, 2020 at 2:08 PM Abhishek Pandit-Subedi
<abhishekpandit@chromium.org> wrote:
>
> Hi Luiz,
>
> On Wed, Aug 26, 2020 at 11:32 PM Luiz Augusto von Dentz
> <luiz.dentz@gmail.com> wrote:
> >
> > Hi Abhishek,
> >
> > On Tue, Aug 18, 2020 at 4:28 PM Abhishek Pandit-Subedi
> > <abhishekpandit@chromium.org> wrote:
> > >
> > > During system suspend, all peer devices are disconnected. On resume, HID
> > > devices will reconnect but audio devices stay disconnected. As a quality
> > > of life improvement, mark audio devices that were disconnected due to
> > > suspend and attempt to reconnect them when the controller resumes (after
> > > a delay for better co-existence with Wi-Fi).
> > >
> > > Signed-off-by: Abhishek Pandit-Subedi <abhishekpandit@chromium.org>
> > > ---
> > >
> > > Changes in v2:
> > > - Refactored to use policy instead of connecting directly in adapter
> > >
> > >  plugins/policy.c | 64 +++++++++++++++++++++++++++++++++++++++++++++---
> > >  src/adapter.c    | 45 ++++++++++++++++++++++++++++++++++
> > >  src/adapter.h    |  6 +++++
> > >  src/main.c       |  1 +
> > >  src/main.conf    |  9 +++++++
> > >  5 files changed, 121 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/plugins/policy.c b/plugins/policy.c
> > > index de51e58b9..b07a997b9 100644
> > > --- a/plugins/policy.c
> > > +++ b/plugins/policy.c
> > > @@ -75,6 +75,9 @@ static const int default_intervals[] = { 1, 2, 4, 8, 16, 32, 64 };
> > >  static int *reconnect_intervals = NULL;
> > >  static size_t reconnect_intervals_len = 0;
> > >
> > > +static const int default_reconnect_delay = 5;
> > > +static int resume_reconnect_delay = 5;
> > > +
> > >  static GSList *reconnects = NULL;
> > >
> > >  static unsigned int service_id = 0;
> > > @@ -93,6 +96,8 @@ struct policy_data {
> > >         uint8_t ct_retries;
> > >         guint tg_timer;
> > >         uint8_t tg_retries;
> > > +
> > > +       bool reconnect_on_resume;
> > >  };
> > >
> > >  static struct reconnect_data *reconnect_find(struct btd_device *dev)
> > > @@ -214,6 +219,7 @@ static gboolean policy_connect_sink(gpointer user_data)
> > >
> > >         data->sink_timer = 0;
> > >         data->sink_retries++;
> > > +       data->reconnect_on_resume = false;
> > >
> > >         service = btd_device_get_service(data->dev, A2DP_SINK_UUID);
> > >         if (service != NULL)
> > > @@ -222,16 +228,20 @@ static gboolean policy_connect_sink(gpointer user_data)
> > >         return FALSE;
> > >  }
> > >
> > > -static void policy_set_sink_timer(struct policy_data *data)
> > > +static void policy_set_sink_timer_internal(struct policy_data *data, int timeout)
> > >  {
> > >         if (data->sink_timer > 0)
> > >                 g_source_remove(data->sink_timer);
> > >
> > > -       data->sink_timer = g_timeout_add_seconds(SINK_RETRY_TIMEOUT,
> > > -                                                       policy_connect_sink,
> > > +       data->sink_timer = g_timeout_add_seconds(timeout, policy_connect_sink,
> > >                                                         data);
> > >  }
> > >
> > > +static void policy_set_sink_timer(struct policy_data *data)
> > > +{
> > > +       policy_set_sink_timer_internal(data, SINK_RETRY_TIMEOUT);
> > > +}
> > > +
> > >  static void sink_cb(struct btd_service *service, btd_service_state_t old_state,
> > >                                                 btd_service_state_t new_state)
> > >  {
> > > @@ -743,10 +753,30 @@ static void reconnect_set_timer(struct reconnect_data *reconnect)
> > >  static void disconnect_cb(struct btd_device *dev, uint8_t reason)
> > >  {
> > >         struct reconnect_data *reconnect;
> > > +       struct btd_service *service;
> > > +       struct policy_data *data;
> > > +       bool do_reconnect = false;
> > >
> > >         DBG("reason %u", reason);
> > >
> > > -       if (reason != MGMT_DEV_DISCONN_TIMEOUT)
> > > +       switch(reason) {
> > > +       case MGMT_DEV_DISCONN_LOCAL_HOST:
> > > +       case MGMT_DEV_DISCONN_REMOTE:
> > > +               do_reconnect = true;
> > > +               break;
> > > +       /* Disconnect due to suspend will queue reconnect on resume for a2dp */
> > > +       case MGMT_DEV_DISCONN_LOCAL_HOST_SUSPEND:
> > > +               service = btd_device_get_service(dev, A2DP_SINK_UUID);
> > > +               if (service && (data = policy_get_data(dev))) {
> > > +                       data->reconnect_on_resume = true;
> > > +               }
> >
> > Can't we just program the timer directly here? Or would that wakeup
> > the system, I would imagine all timers are disabled while suspended
> > which means when the system resumes so does the timers which would
> > then trigger the reconnection logic.
>
> This approach works if every resume is user initiated and keeps the
> device awake long enough to reconnect to the audio device. On
> ChromeOS, this isn't always the case. We have a feature called Dark
> Resume that occurs when the system wakes to handle an event that
> doesn't require user intervention and suspends again without ever
> turning on the screen. See:
> https://chromium.googlesource.com/chromiumos/platform2/+/master/power_manager/docs/dark_resume.md.
> A primary user for this is a periodic wake-up that checks battery
> percentage and shuts down the system if it's too low.

Ok I didn't know such a feature exists in ChromeOS, but doesn't Dark
Resumes should be handled by the kernel instead of each userspace
component? I suppose there quite a few timers that may have side
effects if dark resumes actually resume them.

> One of the tests I ran specifically for this is a suspend stress test
> with a wake time between 2-4s (i.e. suspend_stress_test -c 10
> --wake_min 2 --wake_max 3) which emulates dark resumes. If we set the
> timer when disconnecting, the device would attempt a connection on one
> of the wakeups and fail (since we suspended without completing the
> connection).

We could perhaps check if the kernel is capable of emitting
suspend/resume events and if not just program the timer, or
alternatively add another config option to indicate when the system
supports such concept of Dark Resumes.

> >
> > > +               break;
> > > +       /* All other cases do not result in reconnect */
> > > +       default:
> > > +               break;
> > > +       }
> > > +
> > > +       if (!do_reconnect)
> > >                 return;
> > >
> > >         reconnect = reconnect_find(dev);
> > > @@ -761,6 +791,23 @@ static void disconnect_cb(struct btd_device *dev, uint8_t reason)
> > >         reconnect_set_timer(reconnect);
> > >  }
> > >
> > > +static void controller_resume_cb(uint8_t wake_reason, const bdaddr_t *addr,
> > > +                                       const uint8_t addr_type)
> > > +{
> > > +       struct btd_device *dev;
> > > +       GSList *l;
> > > +
> > > +       /* Check if any devices needed to be reconnected on resume */
> > > +       for (l = devices; l; l = g_slist_next(l)) {
> > > +               struct policy_data *data = l->data;
> > > +
> > > +               if (data->reconnect_on_resume) {
> > > +                       policy_set_sink_timer_internal(data,
> > > +                                                      resume_reconnect_delay);
> > > +               }
> > > +       }
> > > +}
> > > +
> > >  static void conn_fail_cb(struct btd_device *dev, uint8_t status)
> > >  {
> > >         struct reconnect_data *reconnect;
> > > @@ -854,9 +901,17 @@ static int policy_init(void)
> > >         auto_enable = g_key_file_get_boolean(conf, "Policy", "AutoEnable",
> > >                                                                         NULL);
> > >
> > > +       resume_reconnect_delay = g_key_file_get_integer(
> > > +                       conf, "Policy", "ReconnectAudioDelay", &gerr);
> > > +
> > > +       if (gerr) {
> > > +               g_clear_error(&gerr);
> > > +               resume_reconnect_delay = default_reconnect_delay;
> > > +       }
> > >  done:
> > >         if (reconnect_uuids && reconnect_uuids[0] && reconnect_attempts) {
> > >                 btd_add_disconnect_cb(disconnect_cb);
> > > +               btd_add_controller_resume_cb(controller_resume_cb);
> > >                 btd_add_conn_fail_cb(conn_fail_cb);
> > >         }
> > >
> > > @@ -869,6 +924,7 @@ done:
> > >  static void policy_exit(void)
> > >  {
> > >         btd_remove_disconnect_cb(disconnect_cb);
> > > +       btd_remove_controller_resume_cb(controller_resume_cb);
> > >         btd_remove_conn_fail_cb(conn_fail_cb);
> > >
> > >         if (reconnect_uuids)
> > > diff --git a/src/adapter.c b/src/adapter.c
> > > index 5e896a9f0..7526feb9e 100644
> > > --- a/src/adapter.c
> > > +++ b/src/adapter.c
> > > @@ -139,6 +139,7 @@ static GSList *adapter_drivers = NULL;
> > >
> > >  static GSList *disconnect_list = NULL;
> > >  static GSList *conn_fail_list = NULL;
> > > +static GSList *controller_resume_list = NULL;
> > >
> > >  struct link_key_info {
> > >         bdaddr_t bdaddr;
> > > @@ -8766,6 +8767,45 @@ static void connected_callback(uint16_t index, uint16_t length,
> > >         eir_data_free(&eir_data);
> > >  }
> > >
> > > +static void controller_resume_notify(const uint8_t wake_reason,
> > > +                                       const bdaddr_t *addr,
> > > +                                       const uint8_t addr_type)
> > > +{
> > > +       GSList *l;
> > > +
> > > +       for (l = controller_resume_list; l; l = g_slist_next(l)) {
> > > +               btd_controller_resume_cb resume_cb = l->data;
> > > +               resume_cb(wake_reason, addr, addr_type);
> > > +       }
> > > +}
> > > +
> > > +static void controller_resume_callback(uint16_t index, uint16_t length,
> > > +                                      const void *param, void *user_data)
> > > +{
> > > +       const struct mgmt_ev_controller_resume *ev = param;
> > > +       struct btd_adapter *adapter = user_data;
> > > +
> > > +       if (length < sizeof(*ev)) {
> > > +               btd_error(adapter->dev_id, "Too small device resume event");
> > > +               return;
> > > +       }
> > > +
> > > +       DBG("Controller resume with wake event 0x%x", ev->wake_reason);
> > > +
> > > +       controller_resume_notify(ev->wake_reason, &ev->addr.bdaddr,
> > > +                                ev->addr.type);
> > > +}
> > > +
> > > +void btd_add_controller_resume_cb(btd_controller_resume_cb func)
> > > +{
> > > +       controller_resume_list = g_slist_append(controller_resume_list, func);
> > > +}
> > > +
> > > +void btd_remove_controller_resume_cb(btd_controller_resume_cb func)
> > > +{
> > > +       controller_resume_list = g_slist_remove(controller_resume_list, func);
> > > +}
> > > +
> > >  static void device_blocked_callback(uint16_t index, uint16_t length,
> > >                                         const void *param, void *user_data)
> > >  {
> > > @@ -9389,6 +9429,11 @@ static void read_info_complete(uint8_t status, uint16_t length,
> > >                                                 user_passkey_notify_callback,
> > >                                                 adapter, NULL);
> > >
> > > +       mgmt_register(adapter->mgmt, MGMT_EV_CONTROLLER_RESUME,
> > > +                                               adapter->dev_id,
> > > +                                               controller_resume_callback,
> > > +                                               adapter, NULL);
> > > +
> > >         set_dev_class(adapter);
> > >
> > >         set_name(adapter, btd_adapter_get_name(adapter));
> > > diff --git a/src/adapter.h b/src/adapter.h
> > > index f8ac20261..5527e4205 100644
> > > --- a/src/adapter.h
> > > +++ b/src/adapter.h
> > > @@ -67,6 +67,12 @@ typedef void (*btd_conn_fail_cb) (struct btd_device *device, uint8_t status);
> > >  void btd_add_conn_fail_cb(btd_conn_fail_cb func);
> > >  void btd_remove_conn_fail_cb(btd_conn_fail_cb func);
> > >
> > > +typedef void (*btd_controller_resume_cb)(const uint8_t wake_reason,
> > > +                                       const bdaddr_t *addr,
> > > +                                       const uint8_t addr_type);
> > > +void btd_add_controller_resume_cb(btd_controller_resume_cb func);
> > > +void btd_remove_controller_resume_cb(btd_controller_resume_cb func);
> >
> > If we can program the timer just before we suspend this is not really
> > necessary, but if you still thing that would be a good idea to notify
> > Id put it in btd_adapter_driver with a callback for suspend and
> > resume, that way we don't have to maintain multiple lists for each of
> > the callbacks.
>
> The adapter driver seems like a reasonable place to put this so let me
> port that over.
>
> >
> > >  struct btd_adapter *adapter_find(const bdaddr_t *sba);
> > >  struct btd_adapter *adapter_find_by_id(int id);
> > >  void adapter_foreach(adapter_cb func, gpointer user_data);
> > > diff --git a/src/main.c b/src/main.c
> > > index 2c083de67..a1c3e7e9f 100644
> > > --- a/src/main.c
> > > +++ b/src/main.c
> > > @@ -131,6 +131,7 @@ static const char *policy_options[] = {
> > >         "ReconnectAttempts",
> > >         "ReconnectIntervals",
> > >         "AutoEnable",
> > > +       "ReconnectAudioDelay",
> > >         NULL
> > >  };
> > >
> > > diff --git a/src/main.conf b/src/main.conf
> > > index f41203b96..8d74a2aec 100644
> > > --- a/src/main.conf
> > > +++ b/src/main.conf
> > > @@ -198,3 +198,12 @@
> > >  # This includes adapters present on start as well as adapters that are plugged
> > >  # in later on. Defaults to 'false'.
> > >  #AutoEnable=false
> > > +
> > > +# Audio devices that were disconnected due to suspend will be reconnected on
> > > +# resume. ReconnectAudioDelay determines the delay between when the controller
> > > +# resumes from suspend and a connection attempt is made. A longer delay can be
> > > +# better for co-existence with Wi-Fi.
> > > +# The value is in seconds.
> > > +# Default: 5
> > > +#ReconnectAudioDelay = 5
> > > +
> > > --
> > > 2.28.0.297.g1956fa8f8d-goog
> > >
> >
> >
> > --
> > Luiz Augusto von Dentz


-- 
Luiz Augusto von Dentz