ws2812: Fix number of nops for AVR at 8 MHz (#9559) * ws2812: Fix number of nops for AVR at 8 MHz When trying to calculate the number of nops for AVR running at 8 MHz, the value of `w3` is expected to be negative; however, because `F_CPU` is defined in tmk_core/avr.mk with the `UL` suffix, the preprocessor performs its calculations using `unsigned long`, getting a very large positive number instead of the expected negative number; this then results in generating code with a huge number of nops. Fix the broken calculations by performing a comparison before subtraction, so that the unsigned number wraparound does not occur. The keyboard which triggers the problem is `handwired/promethium`; the buggy code silently compiles, but the resulting timings would be completely wrong. * ws2812: Clean up the code after the 8 MHz fix Remove old code which was unsuccessfully trying to clamp negative w1, w2 and w3 values to 0, and set w1_nops, w2_nops and w3_nops directly.
1 files changed, 17 insertions(+), 21 deletions(-) M drivers/avr/ws2812.c
M drivers/avr/ws2812.c => drivers/avr/ws2812.c +17 -21
@@ 67,19 67,27 @@ void ws2812_setleds(LED_TYPE *ledarray, uint16_t number_of_leds) { #define w_onecycles (((F_CPU / 1000) * w_onepulse + 500000) / 1000000) #define w_totalcycles (((F_CPU / 1000) * w_totalperiod + 500000) / 1000000) // w1 - nops between rising edge and falling edge - low #define w1 (w_zerocycles - w_fixedlow) // w2 nops between fe low and fe high #define w2 (w_onecycles - w_fixedhigh - w1) // w3 nops to complete loop #define w3 (w_totalcycles - w_fixedtotal - w1 - w2) #if w1 > 0 # define w1_nops w1 // w1_nops - nops between rising edge and falling edge - low #if w_zerocycles >= w_fixedlow # define w1_nops (w_zerocycles - w_fixedlow) #else # define w1_nops 0 #endif // w2_nops - nops between fe low and fe high #if w_onecycles >= (w_fixedhigh + w1_nops) # define w2_nops (w_onecycles - w_fixedhigh - w1_nops) #else # define w2_nops 0 #endif // w3_nops - nops to complete loop #if w_totalcycles >= (w_fixedtotal + w1_nops + w2_nops) # define w3_nops (w_totalcycles - w_fixedtotal - w1_nops - w2_nops) #else # define w3_nops 0 #endif // The only critical timing parameter is the minimum pulse length of the "0" // Warn or throw error if this timing can not be met with current F_CPU settings. #define w_lowtime ((w1_nops + w_fixedlow) * 1000000) / (F_CPU / 1000) @@ 90,18 98,6 @@ void ws2812_setleds(LED_TYPE *ledarray, uint16_t number_of_leds) { # warning "Please consider a higher clockspeed, if possible" #endif #if w2 > 0 # define w2_nops w2 #else # define w2_nops 0 #endif #if w3 > 0 # define w3_nops w3 #else # define w3_nops 0 #endif #define w_nop1 "nop \n\t" #define w_nop2 "rjmp .+0 \n\t" #define w_nop4 w_nop2 w_nop2