Is tegra_channel_buffer_prepare() in channel.c file is invoked during buffer enqueueing?

Robotics & Edge Computing Jetson & Embedded Systems Jetson Xavier NX
1

In the channel.c driver , we’re using the tegra_channel_buffer_prepare() function to manage buffers and track the framecount variable. I believe this function is invoked when a buffer is being enqueued. Can anyone confirm if tegra_channel_buffer_prepare() is specifically triggered during the enqueue process, and if it’s the correct place to capture and track the current frame count?

4

hello abraham.s,

tegra_channel_buffer_prepare() it means this buffer has been prepared.

may I know what’s the real use-case? you may tracking the vbuf->sequence as following.
note, vb2_buffer_done is the function call for sending a frame to user-space.
for instance, $public_sources/kernel_src/kernel/nvidia/drivers/media/platform/tegra/camera/vi/vi5_fops.c

static void vi5_release_buffer(...)
{
        vbuf->sequence = chan->sequence++;
        vb2_buffer_done(&vbuf->vb2_buf, buf->vb2_state);
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I want to obtain the frame id from the embedded metadata and that to from enqueue buffer. Is it possible to obtain that value during the enqueuing process

6

hello abraham.s,

there’s capture_descr_index, an index into the VI capture descriptor queue.

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