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px4-firmware
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Defer I2C bus resets for the first couple of retries to avoid transient slave errors causing massive retry spam.

This commit is contained in:
px4dev 2013-01-26 17:07:58 -08:00
parent 7864176b5a
commit 33c12d13ad
1 changed files with 11 additions and 8 deletions
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19
apps/drivers/device/i2c.cpp
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@ -120,7 +120,7 @@ I2C::transfer(const uint8_t *send, unsigned send_len, uint8_t *recv, unsigned re
struct i2c_msg_s msgv[2];
unsigned msgs;
int ret;
unsigned tries = 0;
unsigned retry_count = 0;
do {
// debug("transfer out %p/%u in %p/%u", send, send_len, recv, recv_len);
@ -154,13 +154,15 @@ I2C::transfer(const uint8_t *send, unsigned send_len, uint8_t *recv, unsigned re
I2C_SETFREQUENCY(_dev, _frequency);
ret = I2C_TRANSFER(_dev, &msgv[0], msgs);
/* success */
if (ret == OK)
break;
// reset the I2C bus to unwedge on error
up_i2creset(_dev);
/* if we have already retried once, or we are going to give up, then reset the bus */
if ((retry_count >= 1) || (retry_count >= _retries))
up_i2creset(_dev);
} while (tries++ < _retries);
} while (retry_count++ < _retries);
return ret;
@ -170,15 +172,14 @@ int
I2C::transfer(i2c_msg_s *msgv, unsigned msgs)
{
int ret;
unsigned retry_count = 0;
/* force the device address into the message vector */
for (unsigned i = 0; i < msgs; i++)
msgv[i].addr = _address;
unsigned tries = 0;
do {
/*
* I2C architecture means there is an unavoidable race here
* if there are any devices on the bus with a different frequency
@ -187,13 +188,15 @@ I2C::transfer(i2c_msg_s *msgv, unsigned msgs)
I2C_SETFREQUENCY(_dev, _frequency);
ret = I2C_TRANSFER(_dev, msgv, msgs);
/* success */
if (ret == OK)
break;
if (ret != OK)
/* if we have already retried once, or we are going to give up, then reset the bus */
if ((retry_count >= 1) || (retry_count >= _retries))
up_i2creset(_dev);
} while (tries++ < _retries);
} while (retry_count++ < _retries);
return ret;
}