Udelay() for STM32G0

Developers
1

When udelay() (from generic/armcm_timer.h) is used in my code, it compiles for STM32F103, but fails for STM32G0B1.
Well, checking Makefile in stm32 folder shows,that G0 didn’t use armcm_timer code:

timer-src-y := generic/armcm_timer.c
timer-src-$(CONFIG_MACH_STM32F0) := generic/timer_irq.c stm32/stm32f0_timer.c
timer-src-$(CONFIG_MACH_STM32G0) := generic/timer_irq.c stm32/stm32f0_timer.c

Is there any reason, why udelay() not included into stm32f0_timer.c?
Maybe we need small follow-up for this commit? https://github.com/Klipper3d/klipper/commit/700e35c6ac74a64719fbc38fe66386dd422613f3

2

I duplicate my Discord answer here.
It is not intended to be used anywhere: klipper/src/generic/armcm_timer.c at master · Klipper3d/klipper · GitHub

In any place where you want to busy wait, you make your own busy wait: klipper/src/sensor_angle.c at master · Klipper3d/klipper · GitHub, klipper/src/i2c_software.c at master · Klipper3d/klipper · GitHub & etc

Hope that helps.

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3

Thanks.
To reduce duplication, I put ‘weak’ attribute in my code:

image
image714×281 33.3 KB

Is this variant applicable?

4

Originally my goal was to try to avoid adding delays to the code, as we generally try to keep the micro-controller code fast. However, certain devices ultimately require delays so there have been a few cases where udelay() and/or ndelay() are needed.

It probably would be better to introduce generic versions of these functions and share their implementation across all the code.

The armcm variant could likely be renamed to early_udelay() as it has slightly different semantics than typical udelay() users (some boards may need a delay prior to the main timer code being initialized).

Cheers,
-Kevin

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