ESP32-S3 esp32-camera: gdma_disconnect error during esp_camera_deinit() due to ll_cam.c not calling gdma_connect()

[VSkoshchuk]

Checklist

• Checked the issue tracker for similar issues to ensure this is not a duplicate
• Read the documentation to confirm the issue is not addressed there and your configuration is set correctly
• Tested with the latest version to ensure the issue hasn't been fixed

How often does this bug occurs?

always

Expected behavior

When esp32-camera/target/esp32s3/ll_cam.c: ll_cam_deinit() is invoked, the GDMA resources associated with the camera peripheral (LCD_CAM) should be deinitialized and disconnected cleanly without any errors reported by the GDMA driver. Specifically, the gdma_disconnect() call within ll_cam_deinit() should successfully complete, reflecting that the GDMA channel has been properly disconnected from the peripheral it was using for camera data transfers. No errors like "no peripheral is connected to the channel" should occur.

Actual behavior (suspected bug)

Actual behavior (suspected bug):

esp_err_t ll_cam_deinit(cam_obj_t *cam)
{
    if (cam->cam_intr_handle) {
        esp_intr_free(cam->cam_intr_handle);
        cam->cam_intr_handle = NULL;
    }

    if (cam->dma_intr_handle) {
        esp_intr_free(cam->dma_intr_handle);
        cam->dma_intr_handle = NULL;
    }
    gdma_disconnect(cam->dma_channel_handle);
    gdma_del_channel(cam->dma_channel_handle);
    cam->dma_channel_handle = NULL;
    // GDMA.channel[cam->dma_num].in.link.addr = 0x0;

    LCD_CAM.cam_ctrl1.cam_start = 0;
    LCD_CAM.cam_ctrl1.cam_reset = 1;
    LCD_CAM.cam_ctrl1.cam_reset = 0;
    return ESP_OK;
}

When ll_cam_deinit() is called, typically as part of the camera disabling sequence, the system logs an error originating from the GDMA driver:

E (timestamp) gdma: gdma_disconnect(line_num): no peripheral is connected to the channel

This error indicates that the gdma_disconnect() function, called within ll_cam_deinit(), believes the DMA channel was not properly connected to a peripheral via the GDMA driver's API.

Further investigation of the components/esp32-camera/target/esp32s3/ll_cam.c driver reveals that:

• During DMA initialization (ll_cam_dma_init and ll_cam_dma_reset), the GDMA channel is associated with the LCD_CAM peripheral by directly writing to the GDMA.channel[dma_num].in.peri_sel.sel register (e.g., GDMA.channel[cam->dma_num].in.peri_sel.sel = 5;).
• The corresponding gdma_connect() driver API function is never called for the allocated cam->dma_channel_handle.
• However, during deinitialization in ll_cam_deinit(), gdma_disconnect(cam->dma_channel_handle) is called.

This mismatch—connecting to the peripheral via direct register manipulation but attempting to disconnect via the driver's API which expects a prior gdma_connect() call—is the suspected cause of the error. The GDMA driver layer is unaware of the manual connection, leading to the "no peripheral is connected" error upon disconnection.

Error logs or terminal output

E (34820) gdma: gdma_disconnect(319): no peripheral is connected to the channel

Steps to reproduce the behavior

Steps to reproduce the behavior:

1. Initialize the ESP32-S3 camera module using the standard esp_camera_init() function with a valid configuration. This will internally call ll_cam_config(), which subsequently calls ll_cam_dma_init().
2. Perform at least one camera operation that involves data transfer, for example:
   • Take a single picture using esp_camera_fb_get() followed by esp_camera_fb_return().
   • Alternatively, start an MJPEG stream which involves continuous frame capture.
3. Disable or deinitialize the camera using esp_camera_deinit(). This will internally call ll_cam_deinit().
4. Monitor the ESP-IDF system logs (e.g., via serial monitor).
5. Observe that after the camera deinitialization sequence, the error message E (timestamp) gdma: gdma_disconnect(line_num): no peripheral is connected to the channel appears in the logs.

Project release version

v2.0.15

System architecture

Intel/AMD 64-bit (modern PC, older Mac)

Operating system

Linux

Operating system version

Ubuntu 22.04.3 LTS

Shell

CMD

Additional context

Additional context:

• ESP-IDF Version: v5.4.0. The GDMA header file involved is esp_private/gdma.h from this ESP-IDF version.
• Target Board/SoC: ESP32-S3 (specifically, an esp32s3_wroom_1u_n8r2 based board). The issue is within the ESP32-S3 specific low-level camera driver (components/esp32-camera/target/esp32s3/ll_cam.c).
• Camera Module: OV5640.
• Build System: PlatformIO.
• Nature of the bug: The root cause appears to be an API misuse or a missing step in the GDMA driver interaction within the esp32-camera component's ESP32-S3 target code. The gdma_connect() function, which is expected to be called to associate a DMA channel with a peripheral, is seemingly not called during the camera DMA initialization (ll_cam_dma_init). Instead, the peripheral selection (LCD_CAM, which is peripheral ID 5) is done by directly writing to GDMA.channel[cam->dma_num].in.peri_sel.sel = 5; within ll_cam_dma_reset(), which is called by ll_cam_dma_init(). Consequently, when ll_cam_deinit() is later invoked, the gdma_disconnect() call correctly reports that no peripheral was formally "connected" via the driver's API, leading to the "no peripheral is connected to the channel" error.
• Observed Error Log: E (timestamp) gdma: gdma_disconnect(line_num): no peripheral is connected to the channel (e.g., E (409873) gdma: gdma_disconnect(319): no peripheral is connected to the channel).

[DMSimone]

I can confirm this same issue.