[PATCH v8 08/12] virtio-sound: handle VIRTIO_SND_R_PCM_PREPARE

[Emmanouil Pitsidianakis]

Handles the PCM prepare control request. It initializes a PCM stream
when the guests asks for it.

Based-on: 
https://github.com/OpenSynergy/qemu/commit/5a2f350eec5d157b90d9c7b40a8e603f4da92471
Signed-off-by: Igor Skalkin <Igor.Skalkin@opensynergy.com>
Signed-off-by: Anton Yakovlev <Anton.Yakovlev@opensynergy.com>
Signed-off-by: Emmanouil Pitsidianakis <manos.pitsidianakis@linaro.org>
---
 hw/virtio/virtio-snd.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/hw/virtio/virtio-snd.c b/hw/virtio/virtio-snd.c
index a05f637dc3..be6eb2c36d 100644
--- a/hw/virtio/virtio-snd.c
+++ b/hw/virtio/virtio-snd.c
@@ -432,6 +432,27 @@ static uint32_t virtio_snd_pcm_prepare(VirtIOSound *s, 
uint32_t stream_id)
     return VIRTIO_SND_S_OK;
 }
 
+/*
+ * Handles VIRTIO_SND_R_PCM_PREPARE.
+ *
+ * @s: VirtIOSound device
+ * @cmd: The request command queue element from VirtIOSound cmdq field
+ */
+static void virtio_snd_handle_pcm_prepare(VirtIOSound *s,
+                                          virtio_snd_ctrl_command *cmd)
+{
+    uint32_t stream_id;
+    size_t sz = iov_to_buf(cmd->elem->out_sg,
+                           cmd->elem->out_num,
+                           sizeof(virtio_snd_hdr),
+                           &stream_id,
+                           sizeof(stream_id));
+
+    cmd->resp.code = sz == sizeof(uint32_t)
+                   ? virtio_snd_pcm_prepare(s, stream_id)
+                   : VIRTIO_SND_S_BAD_MSG;
+}
+
 /*
  * Handles VIRTIO_SND_R_PCM_START.
  *
@@ -510,6 +531,8 @@ process_cmd(VirtIOSound *s, virtio_snd_ctrl_command *cmd)
         virtio_snd_handle_pcm_set_params(s, cmd);
         break;
     case VIRTIO_SND_R_PCM_PREPARE:
+        virtio_snd_handle_pcm_prepare(s, cmd);
+        break;
     case VIRTIO_SND_R_PCM_RELEASE:
         cmd->resp.code = VIRTIO_SND_S_NOT_SUPP;
         break;
-- 
2.39.2