From a6b5de6a89c82ec8c6d0d7bafb9a377f9035d46b Mon Sep 17 00:00:00 2001
From: Aidan MacDonald <amachronic@protonmail.com>
Date: Wed, 2 Jun 2021 23:44:47 +0100
Subject: [PATCH] x1000: minor adjustments to PWM code

- Change busy loop to wait on the timer flag instead of hoping to
  catch the timer at exactly the right moment... unsurprisingly,
  that did not work well with higher frequency PWM outputs.
- Put GPIO data into a dedicated const array.

Change-Id: I2a920ed265c192da197a18c7242f3205d11636d3
---
 .../target/mips/ingenic_x1000/pwm-x1000.c     | 39 +++++++++++--------
 1 file changed, 23 insertions(+), 16 deletions(-)

diff --git a/firmware/target/mips/ingenic_x1000/pwm-x1000.c b/firmware/target/mips/ingenic_x1000/pwm-x1000.c
index 37d2856c1a..8530a38af5 100644
--- a/firmware/target/mips/ingenic_x1000/pwm-x1000.c
+++ b/firmware/target/mips/ingenic_x1000/pwm-x1000.c
@@ -33,7 +33,6 @@ struct pwm_gpio_data {
 };
 
 struct pwm_state {
-    struct pwm_gpio_data gpio;
     int period_ns;
     int duty_ns;
     int full_ticks;
@@ -41,12 +40,20 @@ struct pwm_state {
     int prescaler;
 };
 
+static const struct pwm_gpio_data pwm_gpios[] = {
+    {GPIO_C, 1 << 25, GPIO_DEVICE(0)},
+    {GPIO_C, 1 << 26, GPIO_DEVICE(1)},
+    {GPIO_C, 1 << 27, GPIO_DEVICE(1)},
+    {GPIO_B, 1 <<  6, GPIO_DEVICE(2)},
+    {GPIO_C, 1 << 24, GPIO_DEVICE(0)},
+};
+
 static struct pwm_state pwm_state[] = {
-    {{GPIO_C, 1 << 25, GPIO_DEVICE(0)}, -1, -1, -1, -1, -1},
-    {{GPIO_C, 1 << 26, GPIO_DEVICE(1)}, -1, -1, -1, -1, -1},
-    {{GPIO_C, 1 << 27, GPIO_DEVICE(1)}, -1, -1, -1, -1, -1},
-    {{GPIO_B, 1 <<  6, GPIO_DEVICE(2)}, -1, -1, -1, -1, -1},
-    {{GPIO_C, 1 << 24, GPIO_DEVICE(0)}, -1, -1, -1, -1, -1},
+    {-1, -1, -1, -1, -1},
+    {-1, -1, -1, -1, -1},
+    {-1, -1, -1, -1, -1},
+    {-1, -1, -1, -1, -1},
+    {-1, -1, -1, -1, -1},
 };
 
 void pwm_init(int chn)
@@ -60,7 +67,8 @@ void pwm_init(int chn)
     st->prescaler = -1;
 
     /* clear GPIO and disable timer */
-    gpio_config(st->gpio.port, st->gpio.pin, GPIO_OUTPUT(0));
+    const struct pwm_gpio_data* pg = &pwm_gpios[chn];
+    gpio_config(pg->port, pg->pin, GPIO_OUTPUT(0));
     jz_clr(TCU_STOP, 1 << chn);
     jz_clr(TCU_ENABLE, 1 << chn);
     jz_set(TCU_STOP, 1 << chn);
@@ -126,11 +134,10 @@ void pwm_set_period(int chn, int period_ns, int duty_ns)
 
     if(full_ticks != st->full_ticks || half_ticks != st->half_ticks) {
         if(enabled) {
-            /* avoid changing PWM settings in the middle of a cycle */
-            unsigned cmp = REG_TCU_CMP_FULL(chn) - 1;
-            long deadline = current_tick + 3;
-            while(REG_TCU_COUNT(chn) < cmp
-               && TIME_BEFORE(current_tick, deadline));
+            /* avoid changing PWM settings in the middle of a cycle,
+             * because for some reason, that is supposed to be "bad" */
+            jz_clr(TCU_FLAG, 1 << chn);
+            while((REG_TCU_FLAG & (1 << chn)) == 0);
         }
 
         /* these can be changed while the timer is running */
@@ -154,15 +161,15 @@ void pwm_enable(int chn)
     jz_set(TCU_ENABLE, 1 << chn);
 
     /* Configure GPIO function */
-    struct pwm_state* st = &pwm_state[chn];
-    gpio_config(st->gpio.port, st->gpio.pin, st->gpio.func);
+    const struct pwm_gpio_data* pg = &pwm_gpios[chn];
+    gpio_config(pg->port, pg->pin, pg->func);
 }
 
 void pwm_disable(int chn)
 {
     /* Set GPIO to output 0 */
-    struct pwm_state* st = &pwm_state[chn];
-    gpio_config(st->gpio.port, st->gpio.pin, GPIO_OUTPUT(0));
+    const struct pwm_gpio_data* pg = &pwm_gpios[chn];
+    gpio_config(pg->port, pg->pin, GPIO_OUTPUT(0));
 
     /* Stop timer */
     jz_clr(TCU_ENABLE, 1 << chn);