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