From: Takashi Iwai <tiwai@suse.de> To: Anton Yakovlev <anton.yakovlev@opensynergy.com> Cc: <virtualization@lists.linux-foundation.org>, <alsa-devel@alsa-project.org>, <virtio-dev@lists.oasis-open.org>, "Michael S. Tsirkin" <mst@redhat.com>, Jaroslav Kysela <perex@perex.cz>, Takashi Iwai <tiwai@suse.com>, <linux-kernel@vger.kernel.org> Subject: Re: [PATCH v6 9/9] ALSA: virtio: introduce device suspend/resume support Date: Tue, 02 Mar 2021 10:11:52 +0100 [thread overview] Message-ID: <s5hr1kxhqcn.wl-tiwai@suse.de> (raw) In-Reply-To: <d9853306-2adf-24fe-935c-f7f8a1295dc3@opensynergy.com> On Tue, 02 Mar 2021 09:09:33 +0100, Anton Yakovlev wrote: > > On 02.03.2021 07:48, Takashi Iwai wrote: > > On Tue, 02 Mar 2021 07:29:20 +0100, > > Anton Yakovlev wrote: > >> > >> 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? > > > > How about calling hw_params(NULL) conditionally in the prepare? > > Then the question is that condition. When ops->prepare() is called, the > substream is in SUSPENDED state or not? If not then we need to track > this in some additional field (and it will make logic a little bit > clumsy, since that field is needed to be carefully handled in other > places). Yes, you'd need to have a suspend/resume PM callback in the driver that flips the internal flag to invalidate the hw_parmas, and in the prepare callback, just call hw_params(NULL) if that flag is set. > > Doing the full stack work in the trigger callback is bad from the API > > design POV; in general the trigger callback is supposed to be as short > > as possible. > > Yeah, but usually original subsystem design does not take into account > para-virtualized devices, which usually have it's own slightly different > reality. And we need to introduce some tricks. The hardware drivers do a lot of more things in either suspend/resume PM callbacks or prepare callback for re-setup of the hardware. We can follow the similar pattern. Heavy-lifting works in the trigger callbacks is really something to avoid. Takashi
WARNING: multiple messages have this Message-ID (diff)
From: Takashi Iwai <tiwai@suse.de> To: Anton Yakovlev <anton.yakovlev@opensynergy.com> Cc: virtio-dev@lists.oasis-open.org, alsa-devel@alsa-project.org, "Michael S. Tsirkin" <mst@redhat.com>, linux-kernel@vger.kernel.org, Takashi Iwai <tiwai@suse.com>, virtualization@lists.linux-foundation.org Subject: Re: [PATCH v6 9/9] ALSA: virtio: introduce device suspend/resume support Date: Tue, 02 Mar 2021 10:11:52 +0100 [thread overview] Message-ID: <s5hr1kxhqcn.wl-tiwai@suse.de> (raw) In-Reply-To: <d9853306-2adf-24fe-935c-f7f8a1295dc3@opensynergy.com> On Tue, 02 Mar 2021 09:09:33 +0100, Anton Yakovlev wrote: > > On 02.03.2021 07:48, Takashi Iwai wrote: > > On Tue, 02 Mar 2021 07:29:20 +0100, > > Anton Yakovlev wrote: > >> > >> 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? > > > > How about calling hw_params(NULL) conditionally in the prepare? > > Then the question is that condition. When ops->prepare() is called, the > substream is in SUSPENDED state or not? If not then we need to track > this in some additional field (and it will make logic a little bit > clumsy, since that field is needed to be carefully handled in other > places). Yes, you'd need to have a suspend/resume PM callback in the driver that flips the internal flag to invalidate the hw_parmas, and in the prepare callback, just call hw_params(NULL) if that flag is set. > > Doing the full stack work in the trigger callback is bad from the API > > design POV; in general the trigger callback is supposed to be as short > > as possible. > > Yeah, but usually original subsystem design does not take into account > para-virtualized devices, which usually have it's own slightly different > reality. And we need to introduce some tricks. The hardware drivers do a lot of more things in either suspend/resume PM callbacks or prepare callback for re-setup of the hardware. We can follow the similar pattern. Heavy-lifting works in the trigger callbacks is really something to avoid. Takashi
next prev parent reply other threads:[~2021-03-02 9:49 UTC|newest] Thread overview: 103+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-02-27 8:59 [PATCH v6 0/9] ALSA: add virtio sound driver Anton Yakovlev 2021-02-27 8:59 ` [virtio-dev] " Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-27 8:59 ` [PATCH v6 1/9] uapi: virtio_ids: add a sound device type ID from OASIS spec Anton Yakovlev 2021-02-27 8:59 ` [virtio-dev] " Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-27 8:59 ` [PATCH v6 2/9] ALSA: virtio: add virtio sound driver Anton Yakovlev 2021-02-27 8:59 ` [virtio-dev] " Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-27 8:59 ` [PATCH v6 3/9] ALSA: virtio: handling control messages Anton Yakovlev 2021-02-27 8:59 ` [virtio-dev] " Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-28 11:04 ` Takashi Iwai 2021-02-28 11:04 ` Takashi Iwai 2021-02-28 18:39 ` Anton Yakovlev 2021-02-28 18:39 ` [virtio-dev] " Anton Yakovlev 2021-02-28 18:39 ` Anton Yakovlev 2021-02-28 18:39 ` Anton Yakovlev 2021-02-27 8:59 ` [PATCH v6 4/9] ALSA: virtio: build PCM devices and substream hardware descriptors Anton Yakovlev 2021-02-27 8:59 ` [virtio-dev] " Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-28 11:15 ` Takashi Iwai 2021-02-28 11:15 ` Takashi Iwai 2021-02-27 8:59 ` [PATCH v6 5/9] ALSA: virtio: handling control and I/O messages for the PCM device Anton Yakovlev 2021-02-27 8:59 ` [virtio-dev] " Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-28 11:27 ` Takashi Iwai 2021-02-28 11:27 ` Takashi Iwai 2021-03-01 9:25 ` Anton Yakovlev 2021-03-01 9:25 ` [virtio-dev] " Anton Yakovlev 2021-03-01 9:25 ` Anton Yakovlev 2021-03-01 9:25 ` Anton Yakovlev 2021-03-01 13:32 ` Takashi Iwai 2021-03-01 13:32 ` Takashi Iwai 2021-03-01 14:47 ` Anton Yakovlev 2021-03-01 14:47 ` [virtio-dev] " Anton Yakovlev 2021-03-01 14:47 ` Anton Yakovlev 2021-03-01 14:47 ` Anton Yakovlev 2021-03-01 14:56 ` Takashi Iwai 2021-03-01 14:56 ` Takashi Iwai 2021-03-01 15:24 ` Anton Yakovlev 2021-03-01 15:24 ` [virtio-dev] " Anton Yakovlev 2021-03-01 15:24 ` Anton Yakovlev 2021-03-01 15:24 ` Anton Yakovlev 2021-03-01 15:30 ` Takashi Iwai 2021-03-01 15:30 ` Takashi Iwai 2021-02-27 8:59 ` [PATCH v6 6/9] ALSA: virtio: PCM substream operators Anton Yakovlev 2021-02-27 8:59 ` [virtio-dev] " Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-28 11:32 ` Takashi Iwai 2021-02-28 11:32 ` Takashi Iwai 2021-03-01 9:29 ` Anton Yakovlev 2021-03-01 9:29 ` [virtio-dev] " Anton Yakovlev 2021-03-01 9:29 ` Anton Yakovlev 2021-03-01 9:29 ` Anton Yakovlev 2021-03-01 13:33 ` Takashi Iwai 2021-03-01 13:33 ` Takashi Iwai 2021-02-27 8:59 ` [PATCH v6 7/9] ALSA: virtio: introduce jack support Anton Yakovlev 2021-02-27 8:59 ` [virtio-dev] " Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-27 8:59 ` [PATCH v6 8/9] ALSA: virtio: introduce PCM channel map support Anton Yakovlev 2021-02-27 8:59 ` [virtio-dev] " Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-27 8:59 ` [PATCH v6 9/9] ALSA: virtio: introduce device suspend/resume support Anton Yakovlev 2021-02-27 8:59 ` [virtio-dev] " Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-27 8:59 ` Anton Yakovlev 2021-02-28 12:05 ` Takashi Iwai 2021-02-28 12:05 ` Takashi Iwai 2021-03-01 10:03 ` Anton Yakovlev 2021-03-01 10:03 ` [virtio-dev] " Anton Yakovlev 2021-03-01 10:03 ` Anton Yakovlev 2021-03-01 10:03 ` Anton Yakovlev 2021-03-01 13:38 ` Takashi Iwai 2021-03-01 13:38 ` Takashi Iwai 2021-03-01 15:30 ` Anton Yakovlev 2021-03-01 15:30 ` [virtio-dev] " Anton Yakovlev 2021-03-01 15:30 ` Anton Yakovlev 2021-03-01 15:30 ` Anton Yakovlev 2021-03-02 6:29 ` Anton Yakovlev 2021-03-02 6:29 ` [virtio-dev] " Anton Yakovlev 2021-03-02 6:29 ` Anton Yakovlev 2021-03-02 6:29 ` Anton Yakovlev 2021-03-02 6:48 ` Takashi Iwai 2021-03-02 6:48 ` Takashi Iwai 2021-03-02 8:09 ` Anton Yakovlev 2021-03-02 8:09 ` [virtio-dev] " Anton Yakovlev 2021-03-02 8:09 ` Anton Yakovlev 2021-03-02 8:09 ` Anton Yakovlev 2021-03-02 9:11 ` Takashi Iwai [this message] 2021-03-02 9:11 ` Takashi Iwai 2021-03-02 15:35 ` Anton Yakovlev 2021-03-02 15:35 ` [virtio-dev] " Anton Yakovlev 2021-03-02 15:35 ` Anton Yakovlev 2021-03-02 15:35 ` Anton Yakovlev
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