logging: Do not set CYCCNTENA to zero in swo backend

The log_backend_swo_init function sets the CYCCNTENA bit of the DWT register to 0, disabling the counter (which is necessary for the timing functions. Avoid overwriting the CYCCNTENA bit. Do not try to set read-only bits. Fixes #34341 Signed-off-by: Andrés Manelli <[email protected]>
zephyrproject-rtos · Apr 22, 2021 · ecf8914 · ecf8914
1 parent 2cff32b
commit ecf8914
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/subsys/logging/log_backend_swo.c b/subsys/logging/log_backend_swo.c
@@ -99,7 +99,8 @@ static void log_backend_swo_init(struct log_backend const *const backend)
  /* Enable unprivileged access to ITM stimulus ports */
  ITM->TPR = 0x0;
  /* Configure Debug Watchpoint and Trace */
- DWT->CTRL = 0x400003FE;
+ DWT->CTRL &= (DWT_CTRL_POSTPRESET_Msk | DWT_CTRL_POSTINIT_Msk | DWT_CTRL_CYCCNTENA_Msk);
+ DWT->CTRL |= (DWT_CTRL_POSTPRESET_Msk | DWT_CTRL_POSTINIT_Msk);
  /* Configure Formatter and Flush Control Register */
  TPI->FFCR = 0x00000100;
  /* Enable ITM, set TraceBusID=1, no local timestamp generation */