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gps: use a max poll timeout of 50ms to check for orb msgs more often

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Before this, I measured a max time spent in poll of 197ms. By checking at
least every 50ms we make sure to not lose any orb messages.
This commit is contained in:
Beat Küng
2016-04-22 09:40:29 +02:00
committed by Lorenz Meier
parent f62324c8a6
commit afefa4d2a0
1 changed files with 14 additions and 10 deletions
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24
src/drivers/gps/gps.cpp
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@@ -68,6 +68,7 @@
#include <px4_time.h>
#include <arch/board/board.h>
#include <drivers/drv_hrt.h>
#include <mathlib/mathlib.h>
#include <systemlib/systemlib.h>
#include <systemlib/scheduling_priorities.h>
#include <systemlib/err.h>
@@ -323,21 +324,25 @@ int GPS::callback(GPSCallbackType type, void *data1, int data2, void *user)
int GPS::pollOrRead(uint8_t *buf, size_t buf_length, int timeout)
{
/* check for new messages. Note that we assume poll_or_read is called with a higher frequency
* than we get new injection messages.
*/
handleInjectDataTopic();
#ifndef __PX4_QURT
/* For non QURT, use the usual polling. */
//Poll only for the serial data. In the same thread we also need to handle orb messages,
//so ideally we would poll on both, the serial fd and orb subscription. Unfortunately the
//two pollings use different underlying mechanisms (at least under posix), which makes this
//impossible. Instead we limit the maximum polling interval and regularly check for new orb
//messages.
//FIXME: add a unified poll() API
const int max_timeout = 50;
pollfd fds[1];
fds[0].fd = _serial_fd;
fds[0].events = POLLIN;
/* Poll for new data, */
int ret = poll(fds, sizeof(fds) / sizeof(fds[0]), timeout);
int ret = poll(fds, sizeof(fds) / sizeof(fds[0]), math::min(max_timeout, timeout));
if (ret > 0) {
/* if we have new data from GPS, go handle it */
@@ -349,16 +354,15 @@ int GPS::pollOrRead(uint8_t *buf, size_t buf_length, int timeout)
* If more bytes are available, we'll go back to poll() again.
*/
usleep(GPS_WAIT_BEFORE_READ * 1000);
return ::read(_serial_fd, buf, buf_length);
ret = ::read(_serial_fd, buf, buf_length);
} else {
return -1;
ret = -1;
}
} else {
return ret;
}
return ret;
#else
/* For QURT, just use read for now, since this doesn't block, we need to slow it down
* just a bit. */