Hi Miao, On Thu, Jul 15, 2021 at 4:21 PM Miao-chen Chou <mcchou@xxxxxxxxxxxx> wrote: > > Hi Luiz, > > On Wed, Jul 14, 2021 at 3:06 PM Luiz Augusto von Dentz > <luiz.dentz@xxxxxxxxx> wrote: > > > > Hi Miao, > > > > On Wed, Jul 14, 2021 at 2:13 PM Miao-chen Chou <mcchou@xxxxxxxxxxxx> wrote: > > > > > > On Fri, Jun 25, 2021 at 10:39 PM Marcel Holtmann <marcel@xxxxxxxxxxxx> wrote: > > > > > > > > Hi Miao-chen, > > > > > > > > > The source of Connect() failures can be divided into the following > > > > > three. > > > > > - bluetoothd's device interface state transition and profile state > > > > > transition > > > > > - Kernel's L2CAP layer state transition > > > > > - Potential HCI error codes returned by the remote device > > > > > > > > > > This also added error-code.txt to describe these error codes. > > > > > > > > > > Reviewed-by: Alain Michaud <alainm@xxxxxxxxxxxx> > > > > > Reviewed-by: Howard Chung <howardchung@xxxxxxxxxx> > > > > > --- > > > > > > > > > > Changes in v2: > > > > > - Add error-code.txt > > > > > - Remove BtdError from return string > > > > > > > > > > doc/error-code.txt | 266 +++++++++++++++++++++++++++++++++++++++++++++ > > > > > src/error.c | 111 +++++++++++++++++++ > > > > > src/error.h | 52 +++++++++ > > > > > 3 files changed, 429 insertions(+) > > > > > create mode 100644 doc/error-code.txt > > > > > > > > please split documentation and code changes into separate patches. > > > > > > > > > > > > > > > > > > diff --git a/doc/error-code.txt b/doc/error-code.txt > > > > > new file mode 100644 > > > > > index 000000000..e91324855 > > > > > --- /dev/null > > > > > +++ b/doc/error-code.txt > > > > > @@ -0,0 +1,266 @@ > > > > > +D-Bus Method Return Error Codes > > > > > +=============================== > > > > > + > > > > > +The motivation of having detailed error codes is to provide context-based > > > > > +failure reasons along with D-Bus method return so that D-Bus clients can > > > > > +build metrics and optimize their application based on these failure reasons. > > > > > +For instance, a client can build retry mechanism for a connection failure or > > > > > +improve the bottleneck of use scenario based on actionable metrics. > > > > > + > > > > > +These error codes are context-based but not necessarily tied to interface or > > > > > +method calls. For instance, if a pairing request failed due to connection > > > > > +failure, connection error would be attached to the method return of Pair(). > > > > > + > > > > > +BR/EDR connection already connected > > > > > +=================================== > > > > > + code: 0x0001 > > > > > + errno: EALREADY, EISCONN > > > > > > > > I would rather see connnection-already-connected instead of 0x0001 in the D-Bus error message. > > > Having a code attached instead of a string description makes it easier > > > for a D-Bus client to interpret and map to corresponding handlers IMO. > > > For instead, a client can simplily use the code in a switch case to > > > perform retry or error reporting. > > > > Well you first need to decode it since the error message is still a > > string, but I would have to agree that doing things like strcmp for > > the error message might be more error prone than extracting the error > > code since the former is more likely to change, the weird thing is > > that D-Bus seems to allow passing more than just a error message > > (https://dbus.freedesktop.org/doc/dbus-specification.html): > > > > 'Errors > > > > Messages of type ERROR are most commonly replies to a METHOD_CALL, > > but may be returned in reply to any kind of message. The message bus > > for example will return an ERROR in reply to a signal emission if the > > bus does not have enough memory to send the signal. > > > > An ERROR may have any arguments, but if the first argument is a > > STRING, it must be an error message. The error message may be logged > > or shown to the user in some way.' > > > > But it looks like libdbus does expect only a string: > > > > https://dbus.freedesktop.org/doc/api/html/group__DBusMessage.html#ga2ab896965aec97fb21293affeed36232 > > > > Well perhaps it needs to constructed manually with the use of > > dbus_message_new_method_return if you want to pass parameters other > > than error_name and error_message so we could include a third one e.g. > > error_code. > It's good to learn that D-Bus allows other types to be attached in > error return. My only concern around introducing new types to the > error return is that it changes how the D-Bus client interprets the > error return. What do you think? I guess it is worth checking if that would break clients, if it does then it is probably a no go, either way it would probably need a specialized error handling to go beyond the err_message so perhaps it is safer to stick to err_name and err_message only and encode the error code on the err_message. > > > > > > > > > > > + > > > > > +Either the profile is already connected or ACL connection is in place. > > > > > + > > > > > +BR/EDR connection page timeout > > > > > +============================== > > > > > + code: 0x0002 > > > > > + errno: EHOSTDOWN > > > > > + > > > > > +Failed due to page timeout. > > > > > + > > > > > +BR/EDR connection profile unavailable > > > > > +===================================== > > > > > + code: 0x0003 > > > > > + errno: ENOPROTOOPT > > > > > + > > > > > +Failed to find connectable services or the target service. > > > > > + > > > > > +BR/EDR connection SDP search > > > > > +============================ > > > > > + code: 0x0004 > > > > > + errno: none > > > > > + > > > > > +Failed to complete the SDP search. > > > > > + > > > > > +BR/EDR connection create socket > > > > > +=============================== > > > > > + code: 0x0005 > > > > > + errno: EIO > > > > > + > > > > > +Failed to create or connect to BT IO socket. This can also indicate hardware > > > > > +failure in the controller. > > > > > + > > > > > +BR/EDR connection invalid arguments > > > > > +=================================== > > > > > + code: 0x0006 > > > > > + errno: EHOSTUNREACH > > > > > + > > > > > +Failed due to invalid arguments. > > > > > + > > > > > +BR/EDR connection not powered > > > > > +============================= > > > > > + code: 0x0007 > > > > > + errno: EHOSTUNREACH > > > > > + > > > > > +Failed due to adapter not powered. > > > > > + > > > > > +BR/EDR connection not supported > > > > > +=============================== > > > > > + code: 0x0008 > > > > > + errno: EOPNOTSUPP, EPROTONOSUPPORT > > > > > + > > > > > +Failed due to unsupported state transition of L2CAP channel or other features > > > > > +either by the local host or the remote. > > > > > + > > > > > +BR/EDR connection bad socket > > > > > +============================ > > > > > + code: 0x0009 > > > > > + errno: EBADFD > > > > > + > > > > > +Failed due to the socket is in bad state. > > > > > + > > > > > +BR/EDR connection memory allocation > > > > > +=================================== > > > > > + code: 0x000A > > > > > + errno: EBADFD > > > > > + > > > > > +Failed to allocate memory in either host stack or controller. > > > > > > > > If this happens, then the code is wrong. Should be an ENOMEM. > > > My mistake, this should be ENOMEM. Corrected in v3. > > > > > > > > > + > > > > > +BR/EDR connection busy > > > > > +====================== > > > > > + code: 0x000B > > > > > + errno: EBUSY > > > > > + > > > > > +Failed due to other ongoing operations, such as pairing, busy L2CAP channel or > > > > > +the operation disallowed by the controller. > > > > > + > > > > > +BR/EDR connection concurrent connection limit > > > > > +============================================= > > > > > + code: 0x000C > > > > > + errno: EMLINK > > > > > + > > > > > +Failed due to reaching the concurrent connection limit to a device. > > > > > + > > > > > +BR/EDR connection timeout > > > > > +========================= > > > > > + code: 0x000D > > > > > + errno: ETIMEDOUT > > > > > + > > > > > +Failed due to connection timeout > > > > > + > > > > > +BR/EDR connection refused > > > > > +========================= > > > > > + code: 0x000E > > > > > + errno: ECONNREFUSED > > > > > + > > > > > +Refused by the remote device due to limited resource, security reason or > > > > > +unacceptable address type. > > > > > + > > > > > +BR/EDR connection aborted by remote > > > > > +=================================== > > > > > + code: 0x000F > > > > > + errno: ECONNRESET > > > > > + > > > > > +Terminated by the remote device due to limited resource or power off. > > > > > + > > > > > +BR/EDR connection aborted by local > > > > > +================================== > > > > > + code: 0x0010 > > > > > + errno: ECONNABORTED > > > > > + > > > > > +Aborted by the local host. > > > > > + > > > > > +BR/EDR connection protocol error > > > > > +================================ > > > > > + code: 0x0011 > > > > > + errno: EPROTO > > > > > + > > > > > +Failed due to LMP protocol error. > > > > > + > > > > > +BR/EDR connection canceled > > > > > +========================== > > > > > + code: 0x0012 > > > > > + errno: none > > > > > + > > > > > +Failed due to cancellation caused by adapter drop, unexpected device drop, or > > > > > +incoming disconnection request before connection request is completed. > > > > > + > > > > > +BR/EDR connection unknown error > > > > > +=============================== > > > > > + code: 0x0013 > > > > > + errno: ENOSYS > > > > > + > > > > > +Failed due to unknown reason. > > > > > + > > > > > +LE connection invalid arguments > > > > > +=============================== > > > > > + code: 0x0101 > > > > > + errno: EINVAL > > > > > + > > > > > +Failed due to invalid arguments. > > > > > + > > > > > +LE connection not powered > > > > > +========================= > > > > > + code: 0x0102 > > > > > + errno: EHOSTUNREACH > > > > > + > > > > > +Failed due to adapter not powered. > > > > > + > > > > > +LE connection not supported > > > > > +=========================== > > > > > + code: 0x0103 > > > > > + errno: EOPNOTSUPP, EPROTONOSUPPORT > > > > > + > > > > > +Failed due to unsupported state transition of L2CAP channel or other features > > > > > +(e.g. LE features) either by the local host or the remote. > > > > > + > > > > > +LE connection already connected > > > > > +=============================== > > > > > + code: 0x0104 > > > > > + errno: EALREADY, EISCONN > > > > > + > > > > > +Either the BT IO is already connected or LE link connection in place. > > > > > + > > > > > +LE connection bad socket > > > > > +======================== > > > > > + code: 0x0105 > > > > > + errno: EBADFD > > > > > + > > > > > +Failed due to the socket is in bad state. > > > > > + > > > > > +LE connection memory allocation > > > > > +=============================== > > > > > + code: 0x0106 > > > > > + errno: ENOMEM > > > > > + > > > > > +Failed to allocate memory in either host stack or controller. > > > > > + > > > > > +LE connection busy > > > > > +================== > > > > > + code: 0x0107 > > > > > + errno: EBUSY > > > > > + > > > > > +Failed due to other ongoing operations, such as pairing, connecting, busy > > > > > +L2CAP channel or the operation disallowed by the controller. > > > > > + > > > > > +LE connection refused > > > > > +===================== > > > > > + code: 0x0108 > > > > > + errno: ECONNREFUSED > > > > > + > > > > > +Failed due to that LE is not enabled or the attempt is refused by the remote > > > > > +device due to limited resource, security reason or unacceptable address type. > > > > > + > > > > > +LE connection create socket > > > > > +=========================== > > > > > + code: 0x0109 > > > > > + errno: EIO > > > > > + > > > > > +Failed to create or connect to BT IO socket. This can also indicate hardware > > > > > +failure in the controller. > > > > > + > > > > > +LE connection timeout > > > > > +===================== > > > > > + code: 0x010A > > > > > + errno: ETIMEDOUT > > > > > + > > > > > +Failed due to connection timeout > > > > > + > > > > > +LE connection concurrent connection limit > > > > > +========================================= > > > > > + code: 0x010B > > > > > + errno: EMLINK > > > > > + > > > > > +Failed due to reaching the synchronous connection limit to a device. > > > > > + > > > > > +LE connection abort by remote > > > > > +============================= > > > > > + code: 0x010C > > > > > + errno: ECONNRESET > > > > > + > > > > > +Aborted by the remote device due to limited resource or power off. > > > > > + > > > > > +LE connection abort by local > > > > > +============================ > > > > > + code: 0x010D > > > > > + errno: ECONNABORTED > > > > > + > > > > > +Aborted by the local host. > > > > > + > > > > > +LE connection link layer protocol error > > > > > +======================================= > > > > > + code: 0x010E > > > > > + errno: EPROTO > > > > > + > > > > > +Failed due to link layer protocol error. > > > > > + > > > > > +LE connection GATT browsing > > > > > +=========================== > > > > > + code: 0x010F > > > > > + errno: none > > > > > + > > > > > +Failed to complete the GATT browsing. > > > > > + > > > > > +LE connection unknown error > > > > > +=========================== > > > > > + code: 0x0110 > > > > > + errno: ENOSYS > > > > > + > > > > > + Failed due to unknown reason. > > > > > diff --git a/src/error.c b/src/error.c > > > > > index 89517075e..73602c4bf 100644 > > > > > --- a/src/error.c > > > > > +++ b/src/error.c > > > > > @@ -27,6 +27,7 @@ > > > > > #include <config.h> > > > > > #endif > > > > > > > > > > +#include <stdio.h> > > > > > #include "gdbus/gdbus.h" > > > > > > > > > > #include "error.h" > > > > > @@ -43,6 +44,12 @@ DBusMessage *btd_error_invalid_args_str(DBusMessage *msg, const char *str) > > > > > "%s", str); > > > > > } > > > > > > > > > > +DBusMessage *btd_error_invalid_args_err(DBusMessage *msg, uint16_t err) > > > > > +{ > > > > > + return g_dbus_create_error(msg, ERROR_INTERFACE ".InvalidArguments", > > > > > + "0x%04X", err); > > > > > +} > > > > > + > > > > > DBusMessage *btd_error_busy(DBusMessage *msg) > > > > > { > > > > > return g_dbus_create_error(msg, ERROR_INTERFACE ".InProgress", > > > > > @@ -79,12 +86,24 @@ DBusMessage *btd_error_in_progress(DBusMessage *msg) > > > > > "In Progress"); > > > > > } > > > > > > > > > > +DBusMessage *btd_error_in_progress_err(DBusMessage *msg, uint16_t err) > > > > > +{ > > > > > + return g_dbus_create_error(msg, ERROR_INTERFACE ".InProgress", "0x%04X", > > > > > + err); > > > > > +} > > > > > + > > > > > DBusMessage *btd_error_not_available(DBusMessage *msg) > > > > > { > > > > > return g_dbus_create_error(msg, ERROR_INTERFACE ".NotAvailable", > > > > > "Operation currently not available"); > > > > > } > > > > > > > > > > +DBusMessage *btd_error_not_available_err(DBusMessage *msg, uint16_t err) > > > > > +{ > > > > > + return g_dbus_create_error(msg, ERROR_INTERFACE ".NotAvailable", > > > > > + "0x%04X", err); > > > > > +} > > > > > + > > > > > DBusMessage *btd_error_does_not_exist(DBusMessage *msg) > > > > > { > > > > > return g_dbus_create_error(msg, ERROR_INTERFACE ".DoesNotExist", > > > > > @@ -121,8 +140,100 @@ DBusMessage *btd_error_not_ready(DBusMessage *msg) > > > > > "Resource Not Ready"); > > > > > } > > > > > > > > > > +DBusMessage *btd_error_not_ready_err(DBusMessage *msg, uint16_t err) > > > > > +{ > > > > > + return g_dbus_create_error(msg, ERROR_INTERFACE ".NotReady", "0x%04X", > > > > > + err); > > > > > +} > > > > > + > > > > > DBusMessage *btd_error_failed(DBusMessage *msg, const char *str) > > > > > { > > > > > return g_dbus_create_error(msg, ERROR_INTERFACE > > > > > ".Failed", "%s", str); > > > > > } > > > > > + > > > > > +DBusMessage *btd_error_failed_err(DBusMessage *msg, uint16_t err) > > > > > +{ > > > > > + return g_dbus_create_error(msg, ERROR_INTERFACE ".Failed", "0x%04X", > > > > > + err); > > > > > +} > > > > > + > > > > > +uint16_t btd_error_bredr_conn_from_errno(int errno_code) > > > > > +{ > > > > > + switch (-errno_code) { > > > > > + case EALREADY: > > > > > + case EISCONN: // Fall through > > > > > > > > Don’t do this Fall through. It is actually not a fall through per se. This is just a statement with two case labels. That is perfectly normal and no compiler should complain. And frankly no C-programmer should be confused if this was intentional or not. > > > Corrected in v3. > > > > > > > > > + return BTD_ERR_BREDR_CONN_ALREADY_CONNECTED; > > > > > + case EHOSTDOWN: > > > > > + return BTD_ERR_BREDR_CONN_PAGE_TIMEOUT; > > > > > + case ENOPROTOOPT: > > > > > + return BTD_ERR_BREDR_CONN_PROFILE_UNAVAILABLE; > > > > > + case EIO: > > > > > + return BTD_ERR_BREDR_CONN_CREATE_SOCKET; > > > > > + case EINVAL: > > > > > + return BTD_ERR_BREDR_CONN_INVALID_ARGUMENTS; > > > > > + case EHOSTUNREACH: > > > > > + return BTD_ERR_BREDR_CONN_ADAPTER_NOT_POWERED; > > > > > + case EOPNOTSUPP: > > > > > + case EPROTONOSUPPORT: // Fall through > > > > > + return BTD_ERR_BREDR_CONN_NOT_SUPPORTED; > > > > > + case EBADFD: > > > > > + return BTD_ERR_BREDR_CONN_BAD_SOCKET; > > > > > + case ENOMEM: > > > > > + return BTD_ERR_BREDR_CONN_MEMORY_ALLOC; > > > > > + case EBUSY: > > > > > + return BTD_ERR_BREDR_CONN_BUSY; > > > > > + case EMLINK: > > > > > + return BTD_ERR_BREDR_CONN_CNCR_CONNECT_LIMIT; > > > > > + case ETIMEDOUT: > > > > > + return BTD_ERR_BREDR_CONN_TIMEOUT; > > > > > + case ECONNREFUSED: > > > > > + return BTD_ERR_BREDR_CONN_REFUSED; > > > > > + case ECONNRESET: > > > > > + return BTD_ERR_BREDR_CONN_ABORT_BY_REMOTE; > > > > > + case ECONNABORTED: > > > > > + return BTD_ERR_BREDR_CONN_ABORT_BY_LOCAL; > > > > > + case EPROTO: > > > > > + return BTD_ERR_BREDR_CONN_PROTO_ERROR; > > > > > + default: > > > > > + return BTD_ERR_BREDR_CONN_UNKNOWN; > > > > > + } > > > > > +} > > > > > + > > > > > +uint16_t btd_error_le_conn_from_errno(int errno_code) > > > > > +{ > > > > > + switch (-errno_code) { > > > > > + case EINVAL: > > > > > + return BTD_ERR_LE_CONN_INVALID_ARGUMENTS; > > > > > + case EHOSTUNREACH: > > > > > + return BTD_ERR_LE_CONN_ADAPTER_NOT_POWERED; > > > > > + case EOPNOTSUPP: > > > > > + case EPROTONOSUPPORT: // Fall through > > > > > + return BTD_ERR_LE_CONN_NOT_SUPPORTED; > > > > > + case EALREADY: > > > > > + case EISCONN: // Fall through > > > > > + return BTD_ERR_LE_CONN_ALREADY_CONNECTED; > > > > > + case EBADFD: > > > > > + return BTD_ERR_LE_CONN_BAD_SOCKET; > > > > > + case ENOMEM: > > > > > + return BTD_ERR_LE_CONN_MEMORY_ALLOC; > > > > > + case EBUSY: > > > > > + return BTD_ERR_LE_CONN_BUSY; > > > > > + case ECONNREFUSED: > > > > > + return BTD_ERR_LE_CONN_REFUSED; > > > > > + case EIO: > > > > > + return BTD_ERR_LE_CONN_CREATE_SOCKET; > > > > > + case ETIMEDOUT: > > > > > + return BTD_ERR_LE_CONN_TIMEOUT; > > > > > + case EMLINK: > > > > > + return BTD_ERR_LE_CONN_SYNC_CONNECT_LIMIT; > > > > > + case ECONNRESET: > > > > > + return BTD_ERR_LE_CONN_ABORT_BY_REMOTE; > > > > > + case ECONNABORTED: > > > > > + return BTD_ERR_LE_CONN_ABORT_BY_LOCAL; > > > > > + case EPROTO: > > > > > + return BTD_ERR_LE_CONN_PROTO_ERROR; > > > > > + default: > > > > > + return BTD_ERR_LE_CONN_UNKNOWN; > > > > > + } > > > > > +} > > > > > diff --git a/src/error.h b/src/error.h > > > > > index 7c8cad066..74d433aca 100644 > > > > > --- a/src/error.h > > > > > +++ b/src/error.h > > > > > @@ -24,22 +24,74 @@ > > > > > */ > > > > > > > > > > #include <dbus/dbus.h> > > > > > +#include <stdint.h> > > > > > > > > > > #define ERROR_INTERFACE "org.bluez.Error" > > > > > > > > > > +/* BR/EDR connection failure reasons > > > > > + * BT_ERR_* should be used as one of the parameters to btd_error_*_err(). > > > > > + */ > > > > > +#define BTD_ERR_BREDR_CONN_ALREADY_CONNECTED 0x0001 > > > > > +#define BTD_ERR_BREDR_CONN_PAGE_TIMEOUT 0x0002 > > > > > +#define BTD_ERR_BREDR_CONN_PROFILE_UNAVAILABLE 0x0003 > > > > > +#define BTD_ERR_BREDR_CONN_SDP_SEARCH 0x0004 > > > > > +#define BTD_ERR_BREDR_CONN_CREATE_SOCKET 0x0005 > > > > > +#define BTD_ERR_BREDR_CONN_INVALID_ARGUMENTS 0x0006 > > > > > +#define BTD_ERR_BREDR_CONN_ADAPTER_NOT_POWERED 0x0007 > > > > > +#define BTD_ERR_BREDR_CONN_NOT_SUPPORTED 0x0008 > > > > > +#define BTD_ERR_BREDR_CONN_BAD_SOCKET 0x0009 > > > > > +#define BTD_ERR_BREDR_CONN_MEMORY_ALLOC 0x000A > > > > > +#define BTD_ERR_BREDR_CONN_BUSY 0x000B > > > > > +#define BTD_ERR_BREDR_CONN_CNCR_CONNECT_LIMIT 0x000C > > > > > +#define BTD_ERR_BREDR_CONN_TIMEOUT 0x000D > > > > > +#define BTD_ERR_BREDR_CONN_REFUSED 0x000E > > > > > +#define BTD_ERR_BREDR_CONN_ABORT_BY_REMOTE 0x000F > > > > > +#define BTD_ERR_BREDR_CONN_ABORT_BY_LOCAL 0x0010 > > > > > +#define BTD_ERR_BREDR_CONN_PROTO_ERROR 0x0011 > > > > > +#define BTD_ERR_BREDR_CONN_CANCELED 0x0012 > > > > > +#define BTD_ERR_BREDR_CONN_UNKNOWN 0x0013 > > > > > + > > > > > +/* LE connection failure reasons > > > > > + * BT_ERR_* should be used as one of the parameters to btd_error_*_err(). > > > > > + */ > > > > > +#define BTD_ERR_LE_CONN_INVALID_ARGUMENTS 0x0101 > > > > > +#define BTD_ERR_LE_CONN_ADAPTER_NOT_POWERED 0x0102 > > > > > +#define BTD_ERR_LE_CONN_NOT_SUPPORTED 0x0103 > > > > > +#define BTD_ERR_LE_CONN_ALREADY_CONNECTED 0x0104 > > > > > +#define BTD_ERR_LE_CONN_BAD_SOCKET 0x0105 > > > > > +#define BTD_ERR_LE_CONN_MEMORY_ALLOC 0x0106 > > > > > +#define BTD_ERR_LE_CONN_BUSY 0x0107 > > > > > +#define BTD_ERR_LE_CONN_REFUSED 0x0108 > > > > > +#define BTD_ERR_LE_CONN_CREATE_SOCKET 0x0109 > > > > > +#define BTD_ERR_LE_CONN_TIMEOUT 0x010A > > > > > +#define BTD_ERR_LE_CONN_SYNC_CONNECT_LIMIT 0x010B > > > > > +#define BTD_ERR_LE_CONN_ABORT_BY_REMOTE 0x010C > > > > > +#define BTD_ERR_LE_CONN_ABORT_BY_LOCAL 0x010D > > > > > +#define BTD_ERR_LE_CONN_PROTO_ERROR 0x010E > > > > > +#define BTD_ERR_LE_CONN_GATT_BROWSE 0x010F > > > > > +#define BTD_ERR_LE_CONN_UNKNOWN 0x0110 > > > > > + > > > > > > > > What is the intention to split BR/EDR and LE here. You do know up-front what connection type you are. Trying to figure out from the error code what connection you have been trying to establish is plain wrong. > > > In fact the up-front connection type is not necessarily known. In the > > > case of dual-mode devices, such as Bose QC35, a D-Bus client can issue > > > Connect(), and it depends on the timing of connection request (adv > > > usually arrive first compared to inquiry result), it can be either > > > BR/EDR or LE link being established. Another aspect of this is the > > > metrics collection, where knowing transport can be handy. For > > > instance, we can associate the certain error to particular use cases > > > at application layer, and that can help targeting the bottleneck to > > > tackle. > > > > > > > > The description is that you want to know exactly where the connection failed. And I think that can be established independent from the transport. > > > Indeed the intention is to know where it failed exactly. However, as > > > mentioned above, transport information is also an important piece of > > > information to know. > > > > > > > > In addition, I don’t like the 0x00?? vs 0x01?? reservation of any number. That always goes bad at some point in the future. > > > As replied above, having a code attached instead of a string > > > description makes it easier for a D-Bus client to interpret and map to > > > corresponding handlers, but I am happy to explore other options as > > > well. > > > > > > > > Regards > > > > > > > > Marcel > > > > > > > Thanks, > > > Miao > > > > > > > > -- > > Luiz Augusto von Dentz > Regards, > Miao -- Luiz Augusto von Dentz
