Improve neopixel on ESP

Greedily grab as much RMT memory as we can. It blocks other RMT
transmit channels but we only use it temporarily anyway. The more
we can grab, the fewer interrupts are needed to keep the transmit
going.

Flickers may still happen due to file system writes but most of the
time the animation just pauses.

On ESP32, move CircuitPython to the second core. This helps NeoPixel
by moving the RMT interrupt to the second core as well.

When testing ESP32 I noticed that settings.toml writes won't apply
until after hard reset. This removes that constraint but still
requires the password to enable the web workflow.

Fixes #3835

Author: tannewt

docs/workflows.md

@@ -71,8 +71,7 @@ Read-only characteristic that returns the UTF-8 encoded version string.
 If the keys `CIRCUITPY_WIFI_SSID` and `CIRCUITPY_WIFI_PASSWORD` are set in `settings.toml`,
 CircuitPython will automatically connect to the given Wi-Fi network on boot and upon reload.
 
-If `CIRCUITPY_WEB_API_PASSWORD` is also set, the web workflow will also start.
-The web workflow will only be enabled if the Wi-Fi connection succeeds upon boot.
+If `CIRCUITPY_WEB_API_PASSWORD` is set, MDNS and the http server for the web workflow will also start.
 
 The webserver is on port 80 unless overridden by `CIRCUITPY_WEB_API_PORT`. It also enables MDNS.
 The name of the board as advertised to the network can be overridden by `CIRCUITPY_WEB_INSTANCE_NAME`.
@@ -84,7 +83,7 @@ Here is an example `/settings.toml`:
 CIRCUITPY_WIFI_SSID="scottswifi"
 CIRCUITPY_WIFI_PASSWORD="secretpassword"
 
-# To enable the the webserver. Change this too!
+# To enable the web workflow. Change this too!
 # Leave the User field blank in the browser.
 CIRCUITPY_WEB_API_PASSWORD="passw0rd"
 

ports/espressif/common-hal/neopixel_write/__init__.c

@@ -66,10 +66,19 @@ void common_hal_neopixel_write(const digitalio_digitalinout_obj_t *digitalinout,
         .clk_src = RMT_CLK_SRC_DEFAULT,
         .resolution_hz = 40000000,
         .trans_queue_depth = 1,
-        .mem_block_symbols = SOC_RMT_MEM_WORDS_PER_CHANNEL,
     };
+
+    // Greedily try and grab as much RMT memory as we can. The more we get, the
+    // smoother the output will be because we'll trigger fewer interrupts. We'll
+    // give it all back once we're done.
     rmt_channel_handle_t channel;
-    CHECK_ESP_RESULT(rmt_new_tx_channel(&config, &channel));
+    esp_err_t result = ESP_ERR_NOT_FOUND;
+    config.mem_block_symbols = SOC_RMT_MEM_WORDS_PER_CHANNEL * SOC_RMT_TX_CANDIDATES_PER_GROUP;
+    while (result == ESP_ERR_NOT_FOUND && config.mem_block_symbols > 0) {
+        result = rmt_new_tx_channel(&config, &channel);
+        config.mem_block_symbols -= SOC_RMT_MEM_WORDS_PER_CHANNEL;
+    }
+    CHECK_ESP_RESULT(result);
 
     size_t ns_per_tick = 1e9 / 40000000;
     uint16_t ws2812_t0h_ticks = WS2812_T0H_NS / ns_per_tick;
@@ -97,7 +106,11 @@ void common_hal_neopixel_write(const digitalio_digitalinout_obj_t *digitalinout,
         }
     };
     rmt_encoder_handle_t encoder;
-    CHECK_ESP_RESULT(rmt_new_bytes_encoder(&encoder_config, &encoder));
+    result = rmt_new_bytes_encoder(&encoder_config, &encoder);
+    if (result != ESP_OK) {
+        rmt_del_channel(channel);
+        return;
+    }
 
     // Wait to make sure we don't append onto the last transmission. This should only be a tick or
     // two.
@@ -111,7 +124,7 @@ void common_hal_neopixel_write(const digitalio_digitalinout_obj_t *digitalinout,
         .loop_count = 0,
         .flags.eot_level = 0
     };
-    esp_err_t result = rmt_transmit(channel, encoder, pixels, (size_t)numBytes, &transmit_config);
+    result = rmt_transmit(channel, encoder, pixels, (size_t)numBytes, &transmit_config);
     if (result != ESP_OK) {
         rmt_del_encoder(encoder);
         rmt_disable(channel);

ports/espressif/esp-idf-config/sdkconfig-esp32.defaults

@@ -28,6 +28,7 @@ CONFIG_PCNT_CTRL_FUNC_IN_IRAM=y
 # ESP System Settings
 #
 CONFIG_ESP_DEFAULT_CPU_FREQ_MHZ_240=y
+CONFIG_ESP_MAIN_TASK_AFFINITY_CPU1=y
 # end of ESP System Settings
 
 #

supervisor/shared/web_workflow/web_workflow.c

@@ -258,7 +258,7 @@ void supervisor_web_workflow_status(void) {
 }
 #endif
 
-bool supervisor_start_web_workflow(bool reload) {
+bool supervisor_start_web_workflow(void) {
     #if CIRCUITPY_WEB_WORKFLOW && CIRCUITPY_WIFI && CIRCUITPY_OS_GETENV
 
     char ssid[33];
@@ -310,7 +310,7 @@ bool supervisor_start_web_workflow(bool reload) {
 
     bool initialized = pool.base.type == &socketpool_socketpool_type;
 
-    if (!initialized && !reload) {
+    if (!initialized) {
         result = common_hal_os_getenv_str("CIRCUITPY_WEB_INSTANCE_NAME", web_instance_name, sizeof(web_instance_name));
         if (result != GETENV_OK || web_instance_name[0] == '\0') {
             strcpy(web_instance_name, MICROPY_HW_BOARD_NAME);

supervisor/shared/web_workflow/web_workflow.h

@@ -36,7 +36,7 @@
 void supervisor_web_workflow_background(void *data);
 bool supervisor_web_workflow_status_dirty(void);
 void supervisor_web_workflow_status(void);
-bool supervisor_start_web_workflow(bool);
+bool supervisor_start_web_workflow(void);
 void supervisor_stop_web_workflow(void);
 
 // Share the MDNS object with user code.

supervisor/shared/workflow.c

@@ -58,7 +58,7 @@ void supervisor_workflow_reset(void) {
     #endif
 
     #if CIRCUITPY_WEB_WORKFLOW
-    bool result = supervisor_start_web_workflow(true);
+    bool result = supervisor_start_web_workflow();
     if (workflow_background_cb.fun) {
         if (result) {
             supervisor_workflow_request_background();
@@ -108,7 +108,7 @@ void supervisor_workflow_start(void) {
     #endif
 
     #if CIRCUITPY_WEB_WORKFLOW
-    if (supervisor_start_web_workflow(false)) {
+    if (supervisor_start_web_workflow()) {
         // Enable background callbacks if web_workflow startup successful
         memset(&workflow_background_cb, 0, sizeof(workflow_background_cb));
         workflow_background_cb.fun = supervisor_web_workflow_background;