[RFC PATCH 00/27] Virtio sound card implementation

[Shreyansh Chouhan]

This patch series aims to implement the virtio sound card
as defined in the virtio specs (v8). The specs can be found
at the following github repo:
https://github.com/oasis-tcs/virtio-spec

This patch series is not complete yet, but here is what's
already been done:

    - The device is initialized properly and is recognized
      by the guest as a sound card device.
    - Output stream works but the output is very noisy. (Which
      is what I wanted coments on.)

What remains to be done:

    - Input streams yet to be done.
    - The jacks are initialized with a default config, but
      they are not mapped to any streams for now.
    - Channel maps are yet to be implemented.

I'd like to request some comments on the following points:

    - The output from the sound card is accompanied by periodic
      white noise. I do not know why this is happening. I tried
      debugging it by writing the buffers to a new wav file and
      sure enough the contents of the file were different at
      some places, but I couldn't find what must be causing it.
      (Relevant patches: #19, #20, #21 and #25.) What steps should
      I take for debugging this?

    - If I try and output a wav file of a different size, that
      sets the period_bytes to 4004, I get an assert failure in
      the object_unref function defined in qom/object.c. (Function
      defined on line #681, assert on line #690.)
                assert(obj->parent == NULL);
      I tried taking a look at the stack trace for when this failure
      happens. In the stacktrace I found out that this happened
      when QEMU was trying to unmap the out_sg from the VirtQueue
      element. This failure doesn't happen if I am using a different
      wav file, that sets the period_bytes to something else.
      (Relevant patches: #19, #20, #21 and #25.)
      What could be causing this problem?

    - What is the suggested way of waiting? When the driver issues
      the VIRTIO_SND_PCM_STOP ctrl command I want to wait for the
      buffers existing in tx vq to be consumed before closing the
      stream.

Shreyansh Chouhan (27):
  virtio-snd: Add virtio sound header file
  virtio-snd: Add jack control structures
  virtio-snd: Add PCM control structures
  virtio-snd: Add chmap control structures
  virtio-snd: Add device implementation structures
  virtio-snd: Add PCI wrapper code for VirtIOSound
  virtio-snd: Add properties for class init
  virtio-snd: Add code for get config function
  virtio-snd: Add code for set config function
  virtio-snd: Add code for the realize function
  virtio-snd: Add macros for logging
  virtio-snd: Add control virtqueue handler
  virtio-snd: Add VIRTIO_SND_R_JACK_INFO handler
  virtio-snd: Add stub for VIRTIO_SND_R_JACK_REMAP handler
  virtio-snd: Add VIRTIO_SND_R_PCM_INFO handler
  virtio-snd: Add VIRITO_SND_R_PCM_SET_PARAMS handle
  virtio-snd: Add VIRTIO_SND_R_PCM_PREPARE handler
  virtio-snd: Add default configs to realize fn
  virtio-snd: Add callback for SWVoiceOut
  virtio-snd: Add VIRITO_SND_R_PCM_START handler
  virtio-snd: Add VIRTIO_SND_R_PCM_STOP handler
  virtio-snd: Add VIRTIO_SND_R_PCM_RELEASE handler
  virtio-snd: Replaced goto with if else
  virtio-snd: Add code to device unrealize function
  virtio-snd: Add tx vq and handler
  virtio-snd: Add event vq and a handler stub
  virtio-snd: Add rx vq and stub handler

 hw/audio/Kconfig               |    5 +
 hw/audio/meson.build           |    1 +
 hw/audio/virtio-snd.c          | 1168 ++++++++++++++++++++++++++++++++
 hw/virtio/meson.build          |    1 +
 hw/virtio/virtio-snd-pci.c     |   72 ++
 include/hw/virtio/virtio-snd.h |  393 +++++++++++
 6 files changed, 1640 insertions(+)
 create mode 100644 hw/audio/virtio-snd.c
 create mode 100644 hw/virtio/virtio-snd-pci.c
 create mode 100644 include/hw/virtio/virtio-snd.h

-- 
2.25.1