From 18a752810f04e3f1933682addd0a6c978efc5cdf Mon Sep 17 00:00:00 2001 From: Manos Pitsidianakis Date: Mon, 23 Oct 2023 15:03:26 +0300 Subject: virtio-sound: implement audio output (TX) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Handle output IO messages in the transmit (TX) virtqueue. It allocates a VirtIOSoundPCMBuffer for each IO message and copies the data buffer to it. When the IO buffer is written to the host's sound card, the guest will be notified that it has been consumed. The lifetime of an IO message is: 1. Guest sends IO message to TX virtqueue. 2. QEMU adds it to the appropriate stream's IO buffer queue. 3. Sometime later, the host audio backend calls the output callback, virtio_snd_pcm_out_cb(), which is defined with an AUD_open_out() call. The callback gets an available number of bytes the backend can receive. Then it writes data from the IO buffer queue to the backend. If at any time a buffer is exhausted, it is returned to the guest as completed. 4. If the guest releases the stream, its buffer queue is flushed by attempting to write any leftover data to the audio backend and releasing all IO messages back to the guest. This is how according to the spec the guest knows the release was successful. Based-on: https://github.com/OpenSynergy/qemu/commit/5a2f350eec5d157b90d9c7b40a8e603f4da92471 Signed-off-by: Igor Skalkin Signed-off-by: Anton Yakovlev Signed-off-by: Manos Pitsidianakis Reviewed-by: Alex Bennée Tested-by: Alex Bennée Message-Id: Acked-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/audio/trace-events | 2 ++ 1 file changed, 2 insertions(+) (limited to 'hw/audio/trace-events') diff --git a/hw/audio/trace-events b/hw/audio/trace-events index 33e24d0..8841081 100644 --- a/hw/audio/trace-events +++ b/hw/audio/trace-events @@ -55,3 +55,5 @@ virtio_snd_handle_pcm_release(uint32_t stream) "VIRTIO_SND_PCM_RELEASE called fo virtio_snd_handle_code(uint32_t val, const char *code) "ctrl code msg val = %"PRIu32" == %s" virtio_snd_handle_chmap_info(void) "VIRTIO_SND_CHMAP_INFO called" virtio_snd_handle_event(void) "event queue callback called" +virtio_snd_pcm_stream_flush(uint32_t stream) "flushing stream %"PRIu32 +virtio_snd_handle_xfer(void) "tx/rx queue callback called" -- cgit v1.1