Re: [PATCH v6 9/9] ALSA: virtio: introduce device suspend/resume support
From: Takashi Iwai
Date: Sun Feb 28 2021 - 07:25:47 EST
On 2021年2月27日 09:59:56 +0100,
Anton Yakovlev wrote:
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All running PCM substreams are stopped on device suspend and restarted
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on device resume.
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Signed-off-by: Anton Yakovlev <anton.yakovlev@xxxxxxxxxxxxxxx>
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---
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sound/virtio/virtio_card.c | 56 +++++++++++++++++++++++++++++++++++
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sound/virtio/virtio_pcm.c | 1 +
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sound/virtio/virtio_pcm_ops.c | 41 ++++++++++++++++++++-----
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3 files changed, 90 insertions(+), 8 deletions(-)
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diff --git a/sound/virtio/virtio_card.c b/sound/virtio/virtio_card.c
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index 59455a562018..c7ae8801991d 100644
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--- a/sound/virtio/virtio_card.c
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+++ b/sound/virtio/virtio_card.c
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@@ -323,6 +323,58 @@ static void virtsnd_remove(struct virtio_device *vdev)
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kfree(snd->event_msgs);
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}
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+#ifdef CONFIG_PM_SLEEP
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+/**
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+ * virtsnd_freeze() - Suspend device.
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+ * @vdev: VirtIO parent device.
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+ *
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+ * Context: Any context.
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+ * Return: 0 on success, -errno on failure.
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+ */
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+static int virtsnd_freeze(struct virtio_device *vdev)
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+{
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+ struct virtio_snd *snd = vdev->priv;
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+
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+ virtsnd_ctl_msg_cancel_all(snd);
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+
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+ vdev->config->del_vqs(vdev);
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+ vdev->config->reset(vdev);
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+
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+ kfree(snd->event_msgs);
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+
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+ /*
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+ * If the virtsnd_restore() fails before re-allocating events, then we
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+ * get a dangling pointer here.
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+ */
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+ snd->event_msgs = NULL;
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+
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+ return 0;
I suppose some cancel of inflight works is needed?
Ditto for the device removal, too.
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--- a/sound/virtio/virtio_pcm.c
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+++ b/sound/virtio/virtio_pcm.c
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@@ -109,6 +109,7 @@ static int virtsnd_pcm_build_hw(struct virtio_pcm_substream *vss,
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SNDRV_PCM_INFO_BATCH |
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SNDRV_PCM_INFO_BLOCK_TRANSFER |
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SNDRV_PCM_INFO_INTERLEAVED |
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+ SNDRV_PCM_INFO_RESUME |
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SNDRV_PCM_INFO_PAUSE;
Actually you don't need to set SNDRV_PCM_INFO_RESUME.
This flag means that the driver supports the full resume procedure,
which isn't often the case; with this, the driver is supposed to
resume the stream exactly from the suspended position.
Most drivers don't set this but implement only the suspend-stop
action. Then the application (or the sound backend) will re-setup the
stream and restart accordingly.
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@@ -309,6 +318,21 @@ static int virtsnd_pcm_trigger(struct snd_pcm_substream *substream, int command)
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int rc;
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switch (command) {
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+ case SNDRV_PCM_TRIGGER_RESUME: {
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+ /*
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+ * We restart the substream by executing the standard command
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+ * sequence.
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+ */
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+ rc = virtsnd_pcm_hw_params(substream, NULL);
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+ if (rc)
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+ return rc;
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+
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+ rc = virtsnd_pcm_prepare(substream);
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+ if (rc)
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+ return rc;
And this won't work at all unless nonatomic PCM ops.
thanks,
Takashi