Re: HCI Set custom bandwidth for AuriStream SCO codec

["Pali Rohár" <pali.rohar@gmail.com>]

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On Tuesday 19 November 2019 18:04:36 Marcel Holtmann wrote:
> Hi Pali,
> 
> >>>>>>>>>>>> to be honest, I would rather see WBS implementation finally
> >>>>>>>>>>>> reach PA before we start digging into this.
> >>>>>>>>>>> 
> >>>>>>>>>>> First I want to finish improving A2DP codec support in pulseaudio. Later
> >>>>>>>>>>> I can look at HSP/HFP profiles. Ideally it should have modular/plugin
> >>>>>>>>>>> extensible design. So the aim is that adding new codec would be very
> >>>>>>>>>>> simple, without need to hack something related to mSBC/WBC, AuriStream
> >>>>>>>>>>> or any other codec.
> >>>>>>>>>> 
> >>>>>>>>>> Well HSP don't have support for codec negotiation, but yes a modular
> >>>>>>>>>> design is probably recommended.
> >>>>>>>>>> 
> >>>>>>>>>>> But for AuriStream I need to set custom SCO parameters as described
> >>>>>>>>>>> below and currently kernel does not support it. This is why I'm asking
> >>>>>>>>>>> how kernel can export for userspace configuration of SCO parameters...
> >>>>>>>>>> 
> >>>>>>>>>> We can always come up with socket options but we got to see the value
> >>>>>>>>>> it would bring since AuriStream don't look that popular among
> >>>>>>>>>> headsets, at least Ive never seem any device advertising it like
> >>>>>>>>>> apt-X, etc.
> >>>>>>>>> 
> >>>>>>>>> Pali clearly has such device and he is willing to work on it. Surely
> >>>>>>>>> that means it is popular enough to be supported...?
> >>>>>>>> 
> >>>>>>>> Just put AT+CSRSF=0,0,0,0,0,7 to google search and you would see that
> >>>>>>>> not only I have such device...
> >>>>>>>> 
> >>>>>>>> So I would really would like to see that kernel finally stops blocking
> >>>>>>>> usage of this AuriStream codec.
> >>>>>>> 
> >>>>>>> we need to figure out on how we do the kernel API to allow you this specific setting.
> >>>>>> 
> >>>>>> Hi Marcel! Kernel API for userspace should be simple. Just add two
> >>>>>> ioctls for retrieving and setting structure with custom parameters:
> >>>>>> 
> >>>>>> syncPktTypes = 0x003F
> >>>>>> bandwidth = 4000
> >>>>>> max_latency = 16
> >>>>>> voice_settings = 0x63
> >>>>>> retx_effort = 2
> >>>>>> 
> >>>>>> Or add more ioctls, one ioctl per parameter. There is already only ioctl
> >>>>>> for voice settings and moreover it is whitelisted only for two values.
> >>>>> 
> >>>>> it is not that simple actually. Most profiles define a certain set of parameters and then they try to configure better settings and only fallback to a specification defined default as last resort.
> >>>> 
> >>>> Ok. I see that there is another "example" configuration for AuriStream
> >>>> with just different syncPktTypes = 0x02BF and bandwidth = 3850.
> >>>> 
> >>>> So it really is not simple as it can be seen.
> >>> 
> >>> currently the stepping for mSBC and CVSD are hard-coded in esco_param_cvsd and esco_param_msbc arrays in hci_conn.c and then selected by the ->setting parameter.
> >>> 
> >>> So either we provide an new socket option (for example BT_VOICE_EXT) or we extend BT_VOICE to allow providing the needed information. However this needs to be flexible array size since we should then be able to encode multiple stepping that are tried in order.
> >>> 
> >>> My preference is that we extend BT_VOICE and not introduce a new socket option. So feel free to propose how we can load the full tables into the SCO socket. I mean we are not really far off actually. The only difference is that currently the tables are in the hci_conn.c file and selected by the provided voice->setting. However nothing really stops us from providing the full table via user space.
> >> 
> >> Ok. I will look at it and I will try to propose how to extend current
> >> BT_VOICE ioctl API for supporting all those new parameters.
> > 
> > Below is inline MIME part with POC patch which try to implement a new
> > IOCTL (currently named BT_VOICE_SETUP) for configuring voice sco
> > settings.
> > 
> > It uses flexible array of parameters <tx_bandwidth, rx_bandwidth,
> > voice_setting, pkt_type, max_latency, retrans_effort>, but with
> > maximally 10 array members (due to usage of static array storage). cvsd
> > codec uses 7 different fallback settings (see voice_setup_cvsd), so for
> > POC 10 should be enough.
> > 
> > Because a new IOCL has different members then old BT_VOICE I rather
> > decided to introduce a new IOCTL and not hacking old IOCTL to accept two
> > different structures.
> > 
> > Please let me know what do you think about this API, if this is a way
> > how to continue or if something different is needed.
> > 
> > -- 
> > Pali Rohár
> > pali.rohar@gmail.com
> > diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
> > index fabee6db0abb..0e9f4ac07220 100644
> > --- a/include/net/bluetooth/bluetooth.h
> > +++ b/include/net/bluetooth/bluetooth.h
> > @@ -122,6 +122,19 @@ struct bt_voice {
> > #define BT_SNDMTU		12
> > #define BT_RCVMTU		13
> > 
> > +#define BT_VOICE_SETUP		14
> > +#define BT_VOICE_SETUP_ARRAY_SIZE 10
> > +struct bt_voice_setup {
> > +	__u8 sco_capable:1;
> > +	__u8 esco_capable:1;
> > +	__u32 tx_bandwidth;
> > +	__u32 rx_bandwidth;
> > +	__u16 voice_setting;
> > +	__u16 pkt_type;
> > +	__u16 max_latency;
> > +	__u8 retrans_effort;
> > +};
> > +
> > __printf(1, 2)
> > void bt_info(const char *fmt, ...);
> > __printf(1, 2)
> > diff --git a/include/net/bluetooth/hci_core.h b/include/net/bluetooth/hci_core.h
> > index 094e61e07030..8f3c161da1c4 100644
> > --- a/include/net/bluetooth/hci_core.h
> > +++ b/include/net/bluetooth/hci_core.h
> > @@ -477,7 +477,7 @@ struct hci_conn {
> > 	__u8		passkey_entered;
> > 	__u16		disc_timeout;
> > 	__u16		conn_timeout;
> > -	__u16		setting;
> > +	struct bt_voice_setup voice_setup[BT_VOICE_SETUP_ARRAY_SIZE];
> > 	__u16		le_conn_min_interval;
> > 	__u16		le_conn_max_interval;
> > 	__u16		le_conn_interval;
> > @@ -897,8 +897,8 @@ static inline struct hci_conn *hci_lookup_le_connect(struct hci_dev *hdev)
> > }
> > 
> > int hci_disconnect(struct hci_conn *conn, __u8 reason);
> > -bool hci_setup_sync(struct hci_conn *conn, __u16 handle);
> > -void hci_sco_setup(struct hci_conn *conn, __u8 status);
> > +int hci_setup_sync(struct hci_conn *conn, __u16 handle);
> > +int hci_sco_setup(struct hci_conn *conn, __u8 status);
> > 
> > struct hci_conn *hci_conn_add(struct hci_dev *hdev, int type, bdaddr_t *dst,
> > 			      u8 role);
> > @@ -920,7 +920,7 @@ struct hci_conn *hci_connect_le(struct hci_dev *hdev, bdaddr_t *dst,
> > struct hci_conn *hci_connect_acl(struct hci_dev *hdev, bdaddr_t *dst,
> > 				 u8 sec_level, u8 auth_type);
> > struct hci_conn *hci_connect_sco(struct hci_dev *hdev, int type, bdaddr_t *dst,
> > -				 __u16 setting);
> > +				 struct bt_voice_setup *voice_setup);
> > int hci_conn_check_link_mode(struct hci_conn *conn);
> > int hci_conn_check_secure(struct hci_conn *conn, __u8 sec_level);
> > int hci_conn_security(struct hci_conn *conn, __u8 sec_level, __u8 auth_type,
> > diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
> > index bd4978ce8c45..0aa2ad98eb80 100644
> > --- a/net/bluetooth/hci_conn.c
> > +++ b/net/bluetooth/hci_conn.c
> > @@ -35,30 +35,6 @@
> > #include "smp.h"
> > #include "a2mp.h"
> > 
> > -struct sco_param {
> > -	u16 pkt_type;
> > -	u16 max_latency;
> > -	u8  retrans_effort;
> > -};
> > -
> > -static const struct sco_param esco_param_cvsd[] = {
> > -	{ EDR_ESCO_MASK & ~ESCO_2EV3, 0x000a,	0x01 }, /* S3 */
> > -	{ EDR_ESCO_MASK & ~ESCO_2EV3, 0x0007,	0x01 }, /* S2 */
> > -	{ EDR_ESCO_MASK | ESCO_EV3,   0x0007,	0x01 }, /* S1 */
> > -	{ EDR_ESCO_MASK | ESCO_HV3,   0xffff,	0x01 }, /* D1 */
> > -	{ EDR_ESCO_MASK | ESCO_HV1,   0xffff,	0x01 }, /* D0 */
> > -};
> > -
> > -static const struct sco_param sco_param_cvsd[] = {
> > -	{ EDR_ESCO_MASK | ESCO_HV3,   0xffff,	0xff }, /* D1 */
> > -	{ EDR_ESCO_MASK | ESCO_HV1,   0xffff,	0xff }, /* D0 */
> > -};
> > -
> > -static const struct sco_param esco_param_msbc[] = {
> > -	{ EDR_ESCO_MASK & ~ESCO_2EV3, 0x000d,	0x02 }, /* T2 */
> > -	{ EDR_ESCO_MASK | ESCO_EV3,   0x0008,	0x02 }, /* T1 */
> > -};
> > -
> 
> can you split this into multiple logical patches. And ensure sending it with git send-email.

I just send it as is to know if such API make sense and should I
continue or not. Preparing patches for git send-email takes a lot of
time and I wanted to know if such API is OK or should be fully
rewritten. So I do not spend on something which does not make sense.
Above patch is not mean to be complete not ready for merge.

-- 
Pali Rohár
pali.rohar@gmail.com

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