fix(rmt): calarify partial receive is not support on esp32

because of lack hardware support

components/esp_driver_mcpwm/include/driver/mcpwm_cap.h

@@ -85,7 +85,7 @@ esp_err_t mcpwm_capture_timer_disable(mcpwm_cap_timer_handle_t cap_timer);
 esp_err_t mcpwm_capture_timer_start(mcpwm_cap_timer_handle_t cap_timer);
 
 /**
- * @brief Start MCPWM capture timer
+ * @brief Stop MCPWM capture timer
  *
  * @param[in] cap_timer MCPWM capture timer, allocated by `mcpwm_new_capture_timer()`
  * @return

components/esp_driver_rmt/src/rmt_rx.c

@@ -286,12 +286,12 @@ esp_err_t rmt_new_rx_channel(const rmt_rx_channel_config_t *config, rmt_channel_
         .pull_up_en = true,
         .pin_bit_mask = BIT64(config->gpio_num),
     };
+    // gpio_config also connects the IO_MUX to the GPIO matrix
     ESP_GOTO_ON_ERROR(gpio_config(&gpio_conf), err, TAG, "config GPIO failed");
     rx_channel->base.gpio_num = config->gpio_num;
     esp_rom_gpio_connect_in_signal(config->gpio_num,
                                    rmt_periph_signals.groups[group_id].channels[channel_id + RMT_RX_CHANNEL_OFFSET_IN_GROUP].rx_sig,
                                    config->flags.invert_in);
-    gpio_func_sel(config->gpio_num, PIN_FUNC_GPIO);
 
     // initialize other members of rx channel
     portMUX_INITIALIZE(&rx_channel->base.spinlock);
@@ -355,6 +355,9 @@ esp_err_t rmt_receive(rmt_channel_handle_t channel, void *buffer, size_t buffer_
 {
     ESP_RETURN_ON_FALSE_ISR(channel && buffer && buffer_size && config, ESP_ERR_INVALID_ARG, TAG, "invalid argument");
     ESP_RETURN_ON_FALSE_ISR(channel->direction == RMT_CHANNEL_DIRECTION_RX, ESP_ERR_INVALID_ARG, TAG, "invalid channel direction");
+#if !SOC_RMT_SUPPORT_RX_PINGPONG
+    ESP_RETURN_ON_FALSE_ISR(!config->flags.en_partial_rx, ESP_ERR_NOT_SUPPORTED, TAG, "partial receive not supported");
+#endif
     rmt_rx_channel_t *rx_chan = __containerof(channel, rmt_rx_channel_t, base);
     size_t per_dma_block_size = 0;
     size_t last_dma_block_size = 0;

components/esp_driver_rmt/src/rmt_tx.c

@@ -355,7 +355,6 @@ esp_err_t rmt_new_tx_channel(const rmt_tx_channel_config_t *config, rmt_channel_
     esp_rom_gpio_connect_out_signal(config->gpio_num,
                                     rmt_periph_signals.groups[group_id].channels[channel_id + RMT_TX_CHANNEL_OFFSET_IN_GROUP].tx_sig,
                                     config->flags.invert_out, false);
-    gpio_func_sel(config->gpio_num, PIN_FUNC_GPIO);
     tx_channel->base.gpio_num = config->gpio_num;
 
     portMUX_INITIALIZE(&tx_channel->base.spinlock);

docs/en/api-reference/peripherals/rmt.rst

@@ -331,7 +331,7 @@ As also discussed in the :ref:`rmt-enable-and-disable-channel`, calling :cpp:fun
 
 - :cpp:member:`rmt_receive_config_t::signal_range_min_ns` specifies the minimal valid pulse duration in either high or low logic levels. A pulse width that is smaller than this value is treated as a glitch, and ignored by the hardware.
 - :cpp:member:`rmt_receive_config_t::signal_range_max_ns` specifies the maximum valid pulse duration in either high or low logic levels. A pulse width that is bigger than this value is treated as **Stop Signal**, and the receiver generates receive-complete event immediately.
-- If the incoming packet is long, that they cannot be stored in the user buffer at once, you can enable the partial reception feature by setting :cpp:member:`rmt_receive_config_t::extra_flags::en_partial_rx` to ``true``. In this case, the driver invokes :cpp:member:`rmt_rx_event_callbacks_t::on_recv_done` callback multiple times during one transaction, when the user buffer is **almost full**. You can check the value of :cpp:member::`rmt_rx_done_event_data_t::is_last` to know if the transaction is about to finish.
+- If the incoming packet is long, that they cannot be stored in the user buffer at once, you can enable the partial reception feature by setting :cpp:member:`rmt_receive_config_t::extra_flags::en_partial_rx` to ``true``. In this case, the driver invokes :cpp:member:`rmt_rx_event_callbacks_t::on_recv_done` callback multiple times during one transaction, when the user buffer is **almost full**. You can check the value of :cpp:member::`rmt_rx_done_event_data_t::is_last` to know if the transaction is about to finish. Please note this features is not supported on all ESP series chips because it relies on hardware abilities like "ping-pong receive" or "DMA receive".
 
 The RMT receiver starts the RX machine after the user calls :cpp:func:`rmt_receive` with the provided configuration above. Note that, this configuration is transaction specific, which means, to start a new round of reception, the user needs to set the :cpp:type:`rmt_receive_config_t` again. The receiver saves the incoming signals into its internal memory block or DMA buffer, in the format of :cpp:type:`rmt_symbol_word_t`.
 

docs/zh_CN/api-reference/peripherals/rmt.rst

@@ -331,7 +331,7 @@ RMT 是一种特殊的通信外设，无法像 SPI 和 I2C 那样发送原始字
 
 - :cpp:member:`rmt_receive_config_t::signal_range_min_ns` 指定高电平或低电平有效脉冲的最小持续时间。如果脉冲宽度小于指定值，硬件会将其视作干扰信号并忽略。
 - :cpp:member:`rmt_receive_config_t::signal_range_max_ns` 指定高电平或低电平有效脉冲的最大持续时间。如果脉冲宽度大于指定值，接收器会将其视作 **停止信号**，并立即生成接收完成事件。
-- 如果传入的数据包很长，无法一次性保存在用户缓冲区中，可以通过将 :cpp:member:`rmt_receive_config_t::extra_flags::en_partial_rx` 设置为 ``true`` 来开启部分接收功能。在这种情况下，当用户缓冲区快满的时候，驱动会多次调用 :cpp:member:`rmt_rx_event_callbacks_t::on_recv_done` 回调函数来通知用户去处理已经收到的数据。你可以检查 :cpp:member::`rmt_rx_done_event_data_t::is_last` 的值来了解当前事务是否已经结束。
+- 如果传入的数据包很长，无法一次性保存在用户缓冲区中，可以通过将 :cpp:member:`rmt_receive_config_t::extra_flags::en_partial_rx` 设置为 ``true`` 来开启部分接收功能。在这种情况下，当用户缓冲区快满的时候，驱动会多次调用 :cpp:member:`rmt_rx_event_callbacks_t::on_recv_done` 回调函数来通知用户去处理已经收到的数据。你可以检查 :cpp:member::`rmt_rx_done_event_data_t::is_last` 的值来了解当前事务是否已经结束。请注意，并不是所有 ESP 系列芯片都支持这个功能，它依赖硬件提供的 “ping-pong 接收” 或者 “DMA 接收” 的能力。
 
 根据以上配置调用 :cpp:func:`rmt_receive` 后，RMT 接收器会启动 RX 机制。注意，以上配置均针对特定事务存在，也就是说，要开启新一轮的接收时，需要再次设置 :cpp:type:`rmt_receive_config_t` 选项。接收器会将传入信号以 :cpp:type:`rmt_symbol_word_t` 的格式保存在内部内存块或 DMA 缓冲区中。