by Abhishek Pandit-Subedi

[permalink] [raw]

Subject: Re: [Bluez PATCH v2 3/3] policy: Reconnect audio on controller resume

Hi Luiz,

On Fri, Aug 28, 2020 at 10:56 AM Luiz Augusto von Dentz
<[email protected]> wrote:
>
> Hi Abhishek,
>
> On Fri, Aug 28, 2020 at 10:31 AM Abhishek Pandit-Subedi
> <[email protected]> wrote:
> >
> > Hi Luiz,
> >
> > On Fri, Aug 28, 2020 at 10:09 AM Luiz Augusto von Dentz
> > <[email protected]> wrote:
> > >
> > > Hi Abhishek,
> > >
> > > On Thu, Aug 27, 2020 at 2:08 PM Abhishek Pandit-Subedi
> > > <[email protected]> wrote:
> > > >
> > > > Hi Luiz,
> > > >
> > > > On Wed, Aug 26, 2020 at 11:32 PM Luiz Augusto von Dentz
> > > > <[email protected]> wrote:
> > > > >
> > > > > Hi Abhishek,
> > > > >
> > > > > On Tue, Aug 18, 2020 at 4:28 PM Abhishek Pandit-Subedi
> > > > > <[email protected]> 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 <[email protected]>
> > > > > > ---
> > > > > >
> > > > > > 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.
> > >
> >
> > I'm not aware of the history around it but I found another page with
> > more context of use cases (like actually letting a user space
> > application run as would happen on a smartphone):
> > https://www.chromium.org/chromium-os/chromiumos-design-docs/lucid-sleep
> >
> > > > 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.
> > >
> >
> > How does the following sound:
> >
> > * On disconnect, I always queue the reconnect but with the resume
> > delay set instead of the interval[0] value. I also set the
> > resume_reconnect flag
> > * On every resume event (or dark resume event), I reset the timer and
> > add resume_delay seconds if resume_reconnect is set
> > * The first time the reconnect_timeout runs, I clear the resume_reconnect flag
> >
> > The delay will only be reapplied if the kernel is capable of emitting
> > suspend/resume events and/or dark resume events.
>
> That should work as well, does full resumes need to reset the timer
> though? Or we don't have any means to identify the resume type? Well
> either way I guess the difference would be quite small since the
> timeout is the same just when it is programmed (on suspend vs on
> resume).

The timer exists to avoid trying to connect at the same time wi-fi may
be trying to associate.

By the way, I had a chance to test all this today and setting the
reconnect timer on disconnect causes the connection to sometimes occur
before the resume event has a chance to run. Depending on the exact
timing, this will likely break the desired dark resume behavior.
I tried `suspend_stress_test --wake_min=1 --wake_max=1 -c 5` and had
the headset reconnect on the 3rd suspend (instead of only at the end)
when using a ResumeDelay of 2.

So I propose the following behavior instead:
* On disconnect, queue a reconnect if reason != SUSPEND. If reason ==
SUSPEND, set reconnect->on_resume = true
* If we support dark resume events (i.e. chromium), set the timer if
resume reason == full resume and reconnect->on_resume = true (this
will probably be a CHROMIUM patch that we carry in our repositories)
* If we support kernel events (and not dark resume), set the timer if
reconnect->on_resume = true (this will be the upstream version)

I will update the resume delay to 2 and test further with some older
Chromebooks. If this reduces the chance of success of BT reconnecting,
we can come back and update this later.

>
> > > > >
> > > > > > + 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
> >
> > Thanks,
> > Abhishek
>
>
>
> --
> Luiz Augusto von Dentz