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STM32: Add never_reset reservation to RGBMatrix init #3441

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Merged
merged 2 commits into from
Sep 20, 2020
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STM32: Add never_reset reservation to RGBMatrix init #3441

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c58bd4c
Add never_reset reservation to RGBMatrix init
hierophect Sep 18, 2020
3a59d30
Remove timer debug messages
hierophect Sep 18, 2020
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1 change: 1 addition & 0 deletions ports/stm/common-hal/rgbmatrix/RGBMatrix.c
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,7 @@ extern void _PM_IRQ_HANDLER(void);
void *common_hal_rgbmatrix_timer_allocate() {
TIM_TypeDef * timer = stm_peripherals_find_timer();
stm_peripherals_timer_reserve(timer);
stm_peripherals_timer_never_reset(timer);
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with "never_reset", does stm_peripherals_timer_free in common_hal_rgbmatrix_timer_free() remain enough to fully deallocate/free/reset the timer?

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I'm sorry, can you rephrase? stm_peripherals_timer_free does undo never reset, is that your question? What do you mean by "remain"?

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CopyQ NkqthX

I'm still not fully familiar/comfortable with the transitions among these states; the naming is a bit different in each port and for each type of managed resource and I'm never entirely confident the semantics are the same. (As a larger issue, it wouldn't hurt to document this for developers reference and to ensure consistency)

My question is whether the state transtion from "timer is in never_reset state" to "timer is in free state" by calling "timer_free" is a correct transition. I think you answered yes.

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@hierophect hierophect Sep 20, 2020 •
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Yes. I think the going concept here is that never_reset is actually a wholly separate option from reserved - it is possible to have an un-reserved pin that is not in never_reset. I suggested joining the two at one point, so that never_reset was strictly a subset of reserved, but I believe we decided against it (I don't fully remember the reason).

Conceptually, reserved is the idea that a pin/peripheral cannot be claimed twice within a single runtime. never_reset is the idea that resetting will not change the reserved status or the pin attributes of that pin/peripheral (basically, immunity status to the reset_all function). To turn off never_reset, you typically call the single-reset function (the not reset-all one) which completely resets all aspects of the pin/peripheral. We have some reset_ok functions which specifically turn off never_reset and nothing else, but they're rarely implemented and even more rarely used.

I'd definitely be down to document this or remove any inconsistencies that you have found. I think we could also revisit whether the two ideas should be combined more concretely in some way - basically, is there ever a scenario where you want something to be in never_reset without it actually being claimed?

return timer;
}

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4 changes: 0 additions & 4 deletions ports/stm/peripherals/timers.c
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Expand Up @@ -195,18 +195,14 @@ TIM_TypeDef * stm_peripherals_find_timer(void) {
// If no results are found, no unclaimed pins with this timer are in this package,
// and it is safe to pick
if (timer_in_package == false && mcu_tim_banks[i] != NULL) {
// DEBUG: print the timer
return mcu_tim_banks[i];
mp_printf(&mp_plat_print, "Timer: %d\n",i);
}
}
//TODO: secondary search for timers outside the pins in the board profile

// Work backwards - higher index timers have fewer pin allocations
for (size_t i = (MP_ARRAY_SIZE(mcu_tim_banks) - 1); i >= 0; i--) {
if ((!stm_timer_reserved[i]) && (mcu_tim_banks[i] != NULL)) {
// DEBUG: print the timer
mp_printf(&mp_plat_print, "Timer: %d\n",i);
return mcu_tim_banks[i];
}
}
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