diff options
| -rw-r--r-- | src/jtag/drivers/jlink.c | 12 |
1 files changed, 5 insertions, 7 deletions
diff --git a/src/jtag/drivers/jlink.c b/src/jtag/drivers/jlink.c index 57e357b..910799c 100644 --- a/src/jtag/drivers/jlink.c +++ b/src/jtag/drivers/jlink.c @@ -1270,16 +1270,14 @@ static bool calculate_swo_prescaler(unsigned int traceclkin_freq, uint32_t trace_freq, uint16_t *prescaler) { unsigned int presc; - double deviation; - - presc = ((1.0 - SWO_MAX_FREQ_DEV) * traceclkin_freq) / trace_freq + 1; - + presc = DIV_ROUND_UP(traceclkin_freq, trace_freq); if (presc > TPIU_ACPR_MAX_SWOSCALER) return false; - deviation = fabs(1.0 - ((double)trace_freq * presc / traceclkin_freq)); - - if (deviation > SWO_MAX_FREQ_DEV) + /* Probe's UART speed must be within 3% of the TPIU's SWO baud rate. */ + unsigned int max_deviation = (traceclkin_freq * 3) / 100; + if (presc * trace_freq < traceclkin_freq - max_deviation || + presc * trace_freq > traceclkin_freq + max_deviation) return false; *prescaler = presc; |