The nRF RTC driver, which is used a system clock driver due to the lack
of SysTick hardware on the SoC, was using too much CPU time in its
_timer_idle_exit() implementation due to the use of 64-bit arithmetical
operations. This was causing the ISR wrapper to add excessive latency to
critical interrupts, causing BLE controller asserts.
This patch addresses the issue by using exclusively RTC ticks instead of
OS ticks, thus avoiding the necessity to convert during
_timer_idle_exit() calls, which are the most critical to interrupt
latency.
In addition the driver is now able to detect setting tick events in the
past due to it being interrupted by a higher priority context, and will
reschedule and trigger the ISR at the same time.
Change-id: I56a3be96b9fdd554c3650012d647af2f0415eb8a
Signed-off-by: Vinayak Chettimada <vinayak.kariappa.chettimada@nordicsemi.no>
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
The nRF5x series SoCs do not implement systick, hence we disable
CORTEX_M_SYSTICK.
Instead, use nRF SoC Series NRF_RTC1 for system clock interfaces.
The kernel system clock interface is implemented using the low
power real time counter NRF_RTC1. NRF_RTC0 is used by the BLE
controller.
In addition, cleanup nRF5x series defconfig to be consistent.
Jira: ZEP-742
Jira: ZEP-1308
Jira: ZEP-1315
Change-id: I0f6cc1836fe0820a65f2cbb02cf5ae7e9eb92e1d
Signed-off-by: Vinayak Chettimada <vinayak.kariappa.chettimada@nordicsemi.no>
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
Carles Cufi