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Mares Icon HD family: send the command as one single write buffer

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The Mares backend used to send the commands by splitting them up into
the two-byte command and the "rest", while waiting for the ACK byte
(0xAA) to come in between the two parts.

That seems to work fine for the serial side, but the the BLE packets, it
seems to cause too much of a delay between the command bytes and the
argument bytes, and the end result is that the Mares doesn't actually
act on the argument bytes at all, and just sends an EOF reply (0xEA).

The Mares app itself does seem to send them as two packets, but
apparently without actually waiting in between, avoiding the issue.

Let's just send the command as a single write, which makes at least my
loaner Mares Quad Air with the BlueLink Pro dongle happy.

We may need to revisit the details of this based on feedback.  But it
should speed up downloading too, by avoiding the roundtrip wait for the
ACK byte.

This affects all the computers in the Mares Icon HD family: Matrix,
Smart, Smart Apnea, Icon HD, Icon HD Net Ready, Puck Pro, Nemo Wide 2,
Puck 2, Quad Air, Smart Air and Quad.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Linus Torvalds 2018-09-26 17:38:14 -07:00
parent e97886a994
commit f57c53470b
1 changed files with 1 additions and 10 deletions
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11
src/mares_iconhd.c
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@ -159,7 +159,7 @@ mares_iconhd_transfer (mares_iconhd_device_t *device,
return DC_STATUS_CANCELLED;
// Send the command header to the dive computer.
status = dc_iostream_write (device->iostream, command, 2, NULL);
status = dc_iostream_write (device->iostream, command, csize, NULL);
if (status != DC_STATUS_SUCCESS) {
ERROR (abstract->context, "Failed to send the command.");
return status;
@ -179,15 +179,6 @@ mares_iconhd_transfer (mares_iconhd_device_t *device,
return DC_STATUS_PROTOCOL;
}
// Send the command payload to the dive computer.
if (csize > 2) {
status = dc_iostream_write (device->iostream, command + 2, csize - 2, 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) {