Anton Yakovlev
2021-Mar-02 06:29 UTC
[PATCH v6 9/9] ALSA: virtio: introduce device suspend/resume support
On 28.02.2021 13:05, Takashi Iwai wrote:> On Sat, 27 Feb 2021 09:59:56 +0100, > Anton Yakovlev wrote: >>[snip]>> --- a/sound/virtio/virtio_pcm.c >> +++ b/sound/virtio/virtio_pcm.c >> @@ -109,6 +109,7 @@ static int virtsnd_pcm_build_hw(struct virtio_pcm_substream *vss, >> SNDRV_PCM_INFO_BATCH | >> SNDRV_PCM_INFO_BLOCK_TRANSFER | >> SNDRV_PCM_INFO_INTERLEAVED | >> + SNDRV_PCM_INFO_RESUME | >> 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.I tried to resume driver without SNDRV_PCM_INFO_RESUME, and alsa-lib called only ops->prepare(). It makes sense for a typical hw, but we have "clean" unconfigured device on resume. And we must set hw parameters as a first step. It means, that code should be more or less the same. And maybe it's better to set SNDRV_PCM_INFO_RESUME, since it allows us to resume substream in any situation (regardless of application behavior). I can refactor code to only send requests from trigger(RESUME) path and not to call ops itself. It should make code more straitforward. What do you say? -- Anton Yakovlev Senior Software Engineer OpenSynergy GmbH Rotherstr. 20, 10245 Berlin