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Use multi-part transactions rather than separate transfers to avoid racing between the ioctl and thread-side interfaces.

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This commit is contained in:
px4dev 2013-01-26 16:16:19 -08:00
parent fd28217e59
commit 52ff9b7d43
1 changed files with 32 additions and 28 deletions
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60
apps/drivers/px4io/px4io.cpp
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@ -818,26 +818,28 @@ PX4IO::io_publish_pwm_outputs()
int
PX4IO::io_reg_set(uint8_t page, uint8_t offset, const uint16_t *values, unsigned num_values)
{
uint8_t buf[_max_transfer + 2];
/* range check the transfer */
if (num_values > ((_max_transfer) / sizeof(*values))) {
debug("io_reg_set: too many registers (%u, max %u)", num_values, _max_transfer / 2);
return -EINVAL;
}
/* set page/offset address */
buf[0] = page;
buf[1] = offset;
/* set up the transfer */
uint8_t addr[2] = {
page,
offset
};
i2c_msg_s msgv[2];
/* copy data into our local transfer buffer */
/* XXX we could use a msgv and two transactions, maybe? */
unsigned datalen = num_values * sizeof(*values);
if (datalen > 0)
memcpy(&buf[2], values, datalen);
msgv[0].flags = 0;
msgv[0].buffer = addr;
msgv[0].length = 2;
msgv[1].flags = I2C_M_NORESTART;
msgv[1].buffer = (uint8_t *)values;
msgv[1].length = num_values * sizeof(*values);
/* perform the transfer */
int ret = transfer(buf, datalen + 2, nullptr, 0);
int ret = transfer(msgv, 2);
if (ret != OK)
debug("io_reg_set: error %d", ret);
return ret;
@ -852,20 +854,22 @@ PX4IO::io_reg_set(uint8_t page, uint8_t offset, uint16_t value)
int
PX4IO::io_reg_get(uint8_t page, uint8_t offset, uint16_t *values, unsigned num_values)
{
uint8_t addr[2];
int ret;
/* set up the transfer */
uint8_t addr[2] = {
page,
offset
};
i2c_msg_s msgv[2];
/* send the address */
addr[0] = page;
addr[1] = offset;
ret = transfer(addr, 2, nullptr, 0);
if (ret != OK) {
debug("io_reg_get: addr error %d", ret);
return ret;
}
msgv[0].flags = 0;
msgv[0].buffer = addr;
msgv[0].length = 2;
msgv[1].flags = I2C_M_READ;
msgv[1].buffer = (uint8_t *)values;
msgv[1].length = num_values * sizeof(*values);
/* now read the data */
ret = transfer(nullptr, 0, (uint8_t *)values, num_values * sizeof(*values));
/* perform the transfer */
int ret = transfer(msgv, 2);
if (ret != OK)
debug("io_reg_get: data error %d", ret);
return ret;
@ -1093,13 +1097,13 @@ PX4IO::write(file *filp, const char *buffer, size_t len)
{
unsigned count = len / 2;
if (count > _max_actuators)
count = _max_actuators;
if (count > _max_actuators)
count = _max_actuators;
if (count > 0) {
int ret = io_reg_set(PX4IO_PAGE_DIRECT_PWM, 0, (uint16_t *)buffer, count);
if (ret != OK)
return ret;
}
return ret;
}
return count * 2;
}
@ -1111,7 +1115,7 @@ namespace
void
test(void)
{
int fd;
int fd;
unsigned servo_count = 0;
unsigned pwm_value = 1000;
int direction = 1;