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Merged
merged 1 commit into from
Nov 25, 2018
Merged

Cellular: more gracefully disconnect. #8772

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2 changes: 1 addition & 1 deletion features/cellular/framework/API/CellularNetwork.h
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Original file line number Diff line number Diff line change
Expand Up @@ -228,7 +228,7 @@ class CellularNetwork {
*/
virtual nsapi_error_t get_attach(AttachStatus &status) = 0;

/** Request detach from a network.
/** Request detach and deregister from a network.
*
* @return NSAPI_ERROR_OK on success
* NSAPI_ERROR_DEVICE_ERROR on failure
Expand Down
34 changes: 26 additions & 8 deletions features/cellular/framework/AT/ATHandler.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -69,7 +69,6 @@ ATHandler::ATHandler(FileHandle *fh, EventQueue &queue, int timeout, const char
_previous_at_timeout(timeout),
_at_send_delay(send_delay),
_last_response_stop(0),
_fh_sigio_set(false),
_processing(false),
_ref_count(1),
_is_fh_usable(true),
Expand Down Expand Up @@ -106,9 +105,7 @@ ATHandler::ATHandler(FileHandle *fh, EventQueue &queue, int timeout, const char
set_tag(&_info_stop, CRLF);
set_tag(&_elem_stop, ")");

_fileHandle->set_blocking(false);

set_filehandle_sigio();
set_file_handle(fh);
}

void ATHandler::set_debug(bool debug_on)
Expand Down Expand Up @@ -151,6 +148,8 @@ FileHandle *ATHandler::get_file_handle()
void ATHandler::set_file_handle(FileHandle *fh)
{
_fileHandle = fh;
_fileHandle->set_blocking(false);
set_filehandle_sigio();
}

void ATHandler::set_is_filehandle_usable(bool usable)
Expand Down Expand Up @@ -309,11 +308,7 @@ void ATHandler::process_oob()

void ATHandler::set_filehandle_sigio()
{
if (_fh_sigio_set) {
return;
}
_fileHandle->sigio(mbed::Callback<void()>(this, &ATHandler::event));
_fh_sigio_set = true;
}

void ATHandler::reset_buffer()
Expand Down Expand Up @@ -1207,3 +1202,26 @@ void ATHandler::debug_print(char *p, int len)
}
#endif // MBED_CONF_CELLULAR_DEBUG_AT
}

bool ATHandler::sync(int timeout_ms)
{
tr_debug("AT sync");
// poll for 10 seconds
for (int i = 0; i < 10; i++) {
lock();
set_at_timeout(timeout_ms, false);
// For sync use an AT command that is supported by all modems and likely not used frequently,
// especially a common response like OK could be response to previous request.
cmd_start("AT+CMEE?");
cmd_stop();
resp_start("+CMEE:");
resp_stop();
restore_at_timeout();
unlock();
if (!_last_err) {
return true;
}
}
tr_error("AT sync failed");
return false;
}
9 changes: 7 additions & 2 deletions features/cellular/framework/AT/ATHandler.h
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Original file line number Diff line number Diff line change
Expand Up @@ -181,6 +181,13 @@ class ATHandler {
*/
void set_is_filehandle_usable(bool usable);

/** Synchronize AT command and response handling to modem.
*
* @param timeout_ms ATHandler timeout when trying to sync. Will be restored when function returns.
* @return true is synchronization was successful, false in case of failure
*/
bool sync(int timeout_ms);

protected:
void event();
#ifdef AT_HANDLER_MUTEX
Expand Down Expand Up @@ -211,8 +218,6 @@ class ATHandler {
uint16_t _at_send_delay;
uint64_t _last_response_stop;

bool _fh_sigio_set;

bool _processing;
int32_t _ref_count;
bool _is_fh_usable;
Expand Down
27 changes: 22 additions & 5 deletions features/cellular/framework/AT/AT_CellularContext.cpp
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Expand Up @@ -28,6 +28,7 @@
#define DEVICE_TIMEOUT 5 * 60 * 1000 // 5 minutes

#if NSAPI_PPP_AVAILABLE
#define AT_SYNC_TIMEOUT 1000 // 1 second timeout
#include "nsapi_ppp.h"
#endif

Expand Down Expand Up @@ -555,6 +556,8 @@ void AT_CellularContext::do_connect()
tr_error("Failed to open data channel!");
call_network_cb(NSAPI_STATUS_DISCONNECTED);
_is_connected = false;
} else {
_is_context_activated = true;
}
}
#else
Expand Down Expand Up @@ -627,13 +630,17 @@ nsapi_error_t AT_CellularContext::disconnect()
_at.lock();
_at.set_file_handle(_at.get_file_handle());
_at.set_is_filehandle_usable(true);
//_at.sync(); // consume extra characters after ppp disconnect, also it may take a while until modem listens AT commands
if (!_at.sync(AT_SYNC_TIMEOUT)) { // consume extra characters after ppp disconnect, also it may take a while until modem listens AT commands
tr_error("AT sync failed after PPP Disconnect");
}
_at.unlock();
#endif // NSAPI_PPP_AVAILABLE
_at.lock();

// deactivate a context only if we have activated
if (_is_context_activated) {
// CGACT and CGATT commands might take up to 3 minutes to respond.
_at.set_at_timeout(180 * 1000);
_is_context_active = false;
size_t active_contexts_count = 0;
_at.cmd_start("AT+CGACT?");
Expand All @@ -659,17 +666,27 @@ nsapi_error_t AT_CellularContext::disconnect()
// 3GPP TS 27.007:
// For EPS, if an attempt is made to disconnect the last PDN connection, then the MT responds with ERROR
if (_is_context_active && (rat < CellularNetwork::RAT_E_UTRAN || active_contexts_count > 1)) {
_at.clear_error();
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Return value is actually meaningless due to clear_error calls?

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Contributor Author

@jarvte jarvte Nov 19, 2018 •
edited
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almost, CGACT can still fail. CGACT is more powerful than commands above. So we try to do thing properly but the last CGACT will finally detach from the network and then it should not matter that the above commands have failed.

_at.cmd_start("AT+CGACT=0,");
_at.write_int(_cid);
_at.cmd_stop_read_resp();
}
}

if (!_at.get_last_error()) {
_is_connected = false;
call_network_cb(NSAPI_STATUS_DISCONNECTED);
if (_new_context_set) {
_at.clear_error();
_at.cmd_start("AT+CGDCONT=");
_at.write_int(_cid);
_at.cmd_stop_read_resp();
}
_at.clear_error();
_at.cmd_start("AT+CGATT=0");
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I guess CellularNetwork::detach should be updated to detach from network.

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added register to CellularNetwork::detach

_at.cmd_stop_read_resp();
_at.restore_at_timeout();
}

_is_connected = false;
call_network_cb(NSAPI_STATUS_DISCONNECTED);
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I guess disconnected event should be handled by +CGEV, when really disconnected.

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Reasons for sending NSAPI_STATUS_DISCONNECTED here:

  • +CGEV is unreliable
  • synchronous disconnect call in PPP mode will also send NSAPI_STATUS_DISCONNECTED before returning so it's on line with PPP now.


return _at.unlock_return_error();
}

Expand Down
3 changes: 3 additions & 0 deletions features/cellular/framework/AT/AT_CellularNetwork.cpp
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Expand Up @@ -350,6 +350,9 @@ nsapi_error_t AT_CellularNetwork::detach()
_at.cmd_start("AT+CGATT=0");
_at.cmd_stop_read_resp();

_at.cmd_start("AT+COPS=2");
_at.cmd_stop_read_resp();

call_network_cb(NSAPI_STATUS_DISCONNECTED);

return _at.unlock_return_error();
Expand Down