Hi Pauli,
On Fri, Jan 27, 2023 at 12:56 PM Pauli Virtanen <pav@xxxxxx> wrote:
>
> Hi,
>
> When the BT adapter does not have the "Connected Isochronous Stream - Central"
> feature, establishing ISO connections fails at a late stage. Namely, we get
> EOPNOTSUPP in connect() due to cis_central_capable(hdev) being false. However,
> at that point BlueZ and the rest of the userspace like sound servers have
> already set up the BAP stuff, and think they are trying to do something that
> should succeed under normal conditions.
>
> It appears the information about what features the adapter actually has should
> be available to BlueZ earlier, and BlueZ should provide accurate information
> about the adapter capabilities to the rest of the userspace.
>
> For LE Audio in particular this is sort of important, because the adapter
> support is not currently there, and only fairly new adapter models have these
> features. There's also a few other bits (Core Sec 4.6, table 4.6) that BlueZ
> might need to know later on, once support for more LE Audio parts is added.
>
> At the moment the ISO sockets are under the experimental feature flag, so I'm
> not sure if this is something that is to be added right now.
>
> Below is a quick hack, which just exposes these bits to the mgmt settings a la
> WBS and handles them in BlueZ. But would this be the right place to put them
> in the first place? Other ideas? Trying to connect() to some random addresses
> from userspace just to probe the feature capability probably is not the right
> thing.
While it is probably a good idea to add as a feature it should be
tight to ISO sockets itself, and perhaps we should have both central
and peripheral flags so we can detect if we need to register the GATT
services when registering the MediaEndpoint.
>
> ---
> doc/mgmt-api.txt | 2 ++
> lib/mgmt.h | 1 +
> profiles/audio/bap.c | 5 +++++
> profiles/audio/media.c | 3 +++
> src/adapter.c | 11 +++++++++++
> src/adapter.h | 6 ++++++
> tools/btmgmt.c | 1 +
> 7 files changed, 29 insertions(+)
>
> include/net/bluetooth/mgmt.h | 1 +
> net/bluetooth/mgmt.c | 6 ++++++
> 2 files changed, 7 insertions(+)
>
>
> diff --git a/doc/mgmt-api.txt b/doc/mgmt-api.txt
> index 90d612ed8..11798629a 100644
> --- a/doc/mgmt-api.txt
> +++ b/doc/mgmt-api.txt
> @@ -333,6 +333,7 @@ Read Controller Information Command
> 16 PHY Configuration
> 17 Wideband Speech
> 18 Quality Report
> + 19 Connected Isochronous Stream Central
>
> This command generates a Command Complete event on success or
> a Command Status event on failure.
> @@ -2926,6 +2927,7 @@ Read Extended Controller Information Command
> 16 PHY Configuration
> 17 Wideband Speech
> 18 Quality Report
> + 19 Connected Isochronous Stream Central
>
> The EIR_Data field contains information about class of device,
> local name and other values. Not all of them might be present. For
> diff --git a/lib/mgmt.h b/lib/mgmt.h
> index 796190cd9..610770491 100644
> --- a/lib/mgmt.h
> +++ b/lib/mgmt.h
> @@ -96,6 +96,7 @@ struct mgmt_rp_read_index_list {
> #define MGMT_SETTING_STATIC_ADDRESS 0x00008000
> #define MGMT_SETTING_PHY_CONFIGURATION 0x00010000
> #define MGMT_SETTING_WIDEBAND_SPEECH 0x00020000
> +#define MGMT_SETTING_CIS_CENTRAL 0x00040000
>
> #define MGMT_OP_READ_INFO 0x0004
> struct mgmt_rp_read_info {
> diff --git a/profiles/audio/bap.c b/profiles/audio/bap.c
> index e5ffb7230..2cd12465a 100644
> --- a/profiles/audio/bap.c
> +++ b/profiles/audio/bap.c
> @@ -1264,6 +1264,11 @@ static int bap_probe(struct btd_service *service)
> return -ENOTSUP;
> }
>
> + if (!btd_adapter_has_feature(adapter, ADAPTER_FEAT_CIS_CENTRAL)) {
> + error("BAP requires CIS Central, but unsupported by adapter");
> + return -ENOTSUP;
In theory this is correct, BAP shall only be used by the central, but
we need to make sure the code doesn't assume bap driver is also needed
when acting as peripheral.
> + }
> +
> /* Ignore, if we were probed for this device already */
> if (data) {
> error("Profile probed twice for the same device!");
> diff --git a/profiles/audio/media.c b/profiles/audio/media.c
> index fbb350889..873dee33e 100644
> --- a/profiles/audio/media.c
> +++ b/profiles/audio/media.c
> @@ -1259,6 +1259,9 @@ static bool experimental_endpoint_supported(struct btd_adapter *adapter)
> if (!btd_adapter_has_exp_feature(adapter, EXP_FEAT_ISO_SOCKET))
> return false;
>
> + if (!btd_adapter_has_feature(adapter, ADAPTER_FEAT_CIS_CENTRAL))
> + return false;
We can act both as central and peripheral so we need to check none of
those are supported then the UUIDs shall not be listed.
> return g_dbus_get_flags() & G_DBUS_FLAG_ENABLE_EXPERIMENTAL;
> }
>
> diff --git a/src/adapter.c b/src/adapter.c
> index aadad4016..2e038ace0 100644
> --- a/src/adapter.c
> +++ b/src/adapter.c
> @@ -10717,6 +10717,17 @@ bool btd_has_kernel_features(uint32_t features)
> return (kernel_features & features) ? true : false;
> }
>
> +bool btd_adapter_has_feature(struct btd_adapter *adapter, uint32_t feature)
> +{
> + size_t i;
> + uint32_t features = 0;
> +
> + if (adapter->supported_settings & MGMT_SETTING_CIS_CENTRAL)
> + features |= ADAPTER_FEAT_CIS_CENTRAL;
> +
> + return features & feature;
> +}
> +
> bool btd_adapter_has_exp_feature(struct btd_adapter *adapter, uint32_t feature)
> {
> size_t i;
> diff --git a/src/adapter.h b/src/adapter.h
> index 78eb069ae..6a9a626bc 100644
> --- a/src/adapter.h
> +++ b/src/adapter.h
> @@ -256,6 +256,12 @@ void btd_adapter_for_each_device(struct btd_adapter *adapter,
>
> bool btd_le_connect_before_pairing(void);
>
> +enum adapter_features {
> + ADAPTER_FEAT_CIS_CENTRAL = 1 << 0,
> +};
> +
> +bool btd_adapter_has_feature(struct btd_adapter *adapter, uint32_t feature);
> +
> enum experimental_features {
> EXP_FEAT_DEBUG = 1 << 0,
> EXP_FEAT_LE_SIMULT_ROLES = 1 << 1,
> diff --git a/tools/btmgmt.c b/tools/btmgmt.c
> index 29f86091f..de614ced1 100644
> --- a/tools/btmgmt.c
> +++ b/tools/btmgmt.c
> @@ -353,6 +353,7 @@ static const char *settings_str[] = {
> "static-addr",
> "phy-configuration",
> "wide-band-speech",
> + "cis-central",
> };
>
> static const char *settings2str(uint32_t settings)
> diff --git a/include/net/bluetooth/mgmt.h b/include/net/bluetooth/mgmt.h
> index 743f6f59dff8..dc284c5f5cbb 100644
> --- a/include/net/bluetooth/mgmt.h
> +++ b/include/net/bluetooth/mgmt.h
> @@ -109,6 +109,7 @@ struct mgmt_rp_read_index_list {
> #define MGMT_SETTING_STATIC_ADDRESS 0x00008000
> #define MGMT_SETTING_PHY_CONFIGURATION 0x00010000
> #define MGMT_SETTING_WIDEBAND_SPEECH 0x00020000
> +#define MGMT_SETTING_CIS_CENTRAL 0x00040000
>
> #define MGMT_OP_READ_INFO 0x0004
> #define MGMT_READ_INFO_SIZE 0
> diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c
> index 0dd30a3beb77..d802faf60f26 100644
> --- a/net/bluetooth/mgmt.c
> +++ b/net/bluetooth/mgmt.c
> @@ -859,6 +859,9 @@ static u32 get_supported_settings(struct hci_dev *hdev)
> hdev->set_bdaddr)
> settings |= MGMT_SETTING_CONFIGURATION;
>
> + if (cis_central_capable(hdev))
> + settings |= MGMT_SETTING_CIS_CENTRAL;
> +
> settings |= MGMT_SETTING_PHY_CONFIGURATION;
>
> return settings;
> @@ -932,6 +935,9 @@ static u32 get_current_settings(struct hci_dev *hdev)
> if (hci_dev_test_flag(hdev, HCI_WIDEBAND_SPEECH_ENABLED))
> settings |= MGMT_SETTING_WIDEBAND_SPEECH;
>
> + if (cis_central_capable(hdev) && iso_enabled())
> + settings |= MGMT_SETTING_CIS_CENTRAL;
I'd drop iso_enabled() from above, the features bits shall indicate
the controller capability only, right now ISO packets can only be
transferred via ISO sockets but this may change in the future if
vendors decide they need a more specialized transport for audio.
> return settings;
> }
>
> --
> 2.39.1
>
--
Luiz Augusto von Dentz
