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authorSergey Vlasov <vsu@altlinux.ru>2021-02-09 00:33:04 +0300
committerGitHub <noreply@github.com>2021-02-09 08:33:04 +1100
commit627ceebef3ed19eceba3642a830ffbf44f4a9e04 (patch)
tree261ce414affa8c15f4973036153ec770553138ef /drivers
parentd2f204c1e3ef92d774feded0ba05a145c2d03cf7 (diff)
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.
Diffstat (limited to 'drivers')
-rw-r--r--drivers/avr/ws2812.c38
1 files changed, 17 insertions, 21 deletions
diff --git a/drivers/avr/ws2812.c b/drivers/avr/ws2812.c
index dd2ef89912..77c492cd4c 100644
--- a/drivers/avr/ws2812.c
+++ b/drivers/avr/ws2812.c
@@ -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