FlapJackApps/libdc
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Mares bluetooth support tweaks

Browse Source 
So it turns out that we really shouldn't send the command and arguments
as one single packet in all situations, because at least the Mares
Matrix really seems to want that "wait for ACK before sending
arguments".  See commit 59bfb0f3189b ("Add support for the Mares
Matrix") for details.

Also, because bluetooth is slow (and it looks like it's particularly
slow for us with the Qt bluetooth code for some reason), we don't want
to ask for big packets of data, because it seems to cause a buffer
overflow on the BlueLink Pro when the serial data from the dive computer
arrives faster than the bluetooth data can be sent to the downloading
side.

So when using the BLE transport, limit the packet size to 128 bytes and
disable the command splitting.

With this, I can download hundreds of kB of data from the Mares Quad Air
successfully over BLE. It's *slow*, but it works.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2018-09-27 10:36:00 -07:00
parent f57c53470b
commit 5be8c17ea1
1 changed files with 43 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

44
src/mares_iconhd.c
View File

@ -72,6 +72,7 @@ typedef struct mares_iconhd_device_t {
unsigned char version[140];
unsigned int model;
unsigned int packetsize;
unsigned int splitcommand;
} mares_iconhd_device_t;
static dc_status_t mares_iconhd_device_set_fingerprint (dc_device_t *abstract, const unsigned char data[], unsigned int size);
@ -152,14 +153,17 @@ mares_iconhd_transfer (mares_iconhd_device_t *device,
{
dc_status_t status = DC_STATUS_SUCCESS;
dc_device_t *abstract = (dc_device_t *) device;
unsigned int split_csize;
assert (csize >= 2);
if (device_is_cancelled (abstract))
return DC_STATUS_CANCELLED;
split_csize = device->splitcommand ? 2 : csize;
// Send the command header to the dive computer.
status = dc_iostream_write (device->iostream, command, csize, NULL);
status = dc_iostream_write (device->iostream, command, split_csize, NULL);
if (status != DC_STATUS_SUCCESS) {
ERROR (abstract->context, "Failed to send the command.");
return status;
@ -179,6 +183,15 @@ mares_iconhd_transfer (mares_iconhd_device_t *device,
return DC_STATUS_PROTOCOL;
}
// Send any remaining command payload to the dive computer.
if (csize > split_csize) {
status = dc_iostream_write (device->iostream, command + split_csize, csize - split_csize, NULL);
if (status != DC_STATUS_SUCCESS) {
ERROR (abstract->context, "Failed to send the command.");
return status;
}
}
// Read the packet.
status = dc_iostream_read (device->iostream, answer, asize, NULL);
if (status != DC_STATUS_SUCCESS) {
@ -228,6 +241,15 @@ mares_iconhd_device_open (dc_device_t **out, dc_context_t *context, dc_iostream_
device->model = 0;
device->packetsize = 0;
/*
* At least the Mares Matrix needs the command to be split into
* base and argument, with a wait for the ACK byte in between.
*
* See commit 59bfb0f3189b ("Add support for the Mares Matrix")
* for details.
*/
device->splitcommand = 1;
// Set the serial communication protocol (115200 8E1).
status = dc_iostream_configure (device->iostream, 115200, 8, DC_PARITY_EVEN, DC_STOPBITS_ONE, DC_FLOWCONTROL_NONE);
if (status != DC_STATUS_SUCCESS) {
@ -301,6 +323,26 @@ mares_iconhd_device_open (dc_device_t **out, dc_context_t *context, dc_iostream_
break;
}
if (dc_iostream_get_transport(device->iostream) == DC_TRANSPORT_BLE) {
/*
* Don't ask for larger amounts of data with the BLE
* transport - it will fail. I suspect there is a buffer
* overflow in the BlueLink Pro dongle when bluetooth is
* slower than the serial protocol that the dongle talks to
* the dive computer.
*/
if (device->packetsize > 128)
device->packetsize = 128;
/*
* With BLE, don't wait for ACK before sending the arguments
* to a command.
*
* There is some timing issue that makes that take too long
* and causes the command to be aborted.
*/
device->splitcommand = 0;
}
*out = (dc_device_t *) device;
return DC_STATUS_SUCCESS;