From 3f5dc472965e6a5b8efe60e33c7b6c2d18d92008 Mon Sep 17 00:00:00 2001 From: Stefan Kerkmann Date: Mon, 11 Jul 2022 15:17:05 +0200 Subject: [Core] Use polled waiting on ChibiOS platforms that support it (#17607) * Use polled waiting on platforms that support it Due to context switching overhead waiting a very short amount of time on a sleeping thread is often not accurate and in fact not usable for timing critical usage i.e. in a driver. Thus we use polled waiting for ranges in the us range on platforms that support it instead. The fallback is the thread sleeping mechanism. This includes: * ARM platforms with CYCCNT register (ARMv7, ARMv8) this is incremented at CPU clock frequency * GD32VF103 RISC-V port with CSR_MCYCLE register this is incremented at CPU clock frequency * RP2040 ARMv6 port which uses the integrated timer peripheral which is incremented with a fixed 1MHz frequency * Use wait_us() instead of chSysPolledDelayX ...as it is powered by busy waiting now. * Add chibios waiting methods test bench --- platforms/chibios/bootloaders/rp2040.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'platforms/chibios/bootloaders') diff --git a/platforms/chibios/bootloaders/rp2040.c b/platforms/chibios/bootloaders/rp2040.c index 13a54036ef..bedc00f32e 100644 --- a/platforms/chibios/bootloaders/rp2040.c +++ b/platforms/chibios/bootloaders/rp2040.c @@ -43,9 +43,8 @@ void __late_init(void) { if (magic_location != magic_token) { magic_location = magic_token; // ChibiOS is not initialized at this point, so sleeping is only - // possible via busy waiting. The internal timer peripheral is running - // at this point with a precision of 1us. - chSysPolledDelayX(MS2RTC(1 * MHZ, RP2040_BOOTLOADER_DOUBLE_TAP_RESET_TIMEOUT)); + // possible via busy waiting. + wait_us(RP2040_BOOTLOADER_DOUBLE_TAP_RESET_TIMEOUT * 1000U); magic_location = 0; return; } -- cgit v1.2.3