Hi
> -----Original Message-----
> From: Takashi Sakamoto <o-takashi@xxxxxxxxxxxxx>
> Sent: Wednesday, December 26, 2018 9:35 PM
>
> Hi,
>
> On Wed, Dec 26, 2018 at 11:28:11AM +0000, S.j. Wang wrote:
> > In the case that alsa driver can't support period wakeup, we need to
> > set the no period wakeup flag
> >
> > Signed-off-by: Shengjiu Wang <shengjiu.wang@xxxxxxx>
> > ---
> > aplay/aplay.c | 13 +++++++++++++
> > 1 file changed, 13 insertions(+)
> >
> > diff --git a/aplay/aplay.c b/aplay/aplay.c index
> > efc1eb4cae3a..4f562bfe2884 100644
> > --- a/aplay/aplay.c
> > +++ b/aplay/aplay.c
> > @@ -137,6 +137,7 @@ static int use_strftime = 0; volatile static int
> > recycle_capture_file = 0; static long term_c_lflag = -1; static int
> > dump_hw_params = 0;
> > +static int no_period_wakeup = 0;
> >
> > static int fd = -1;
> > static off64_t pbrec_count = LLONG_MAX, fdcount; @@ -243,6 +244,7
> @@
> > _("Usage: %s [OPTION]... [FILE]...\n"
> > " --use-strftime apply the strftime facility to the output file name\n"
> > " --dump-hw-params dump hw_params of the device\n"
> > " --fatal-errors treat all errors as fatal\n"
> > +" --no-period-wakeup set no period wakeup flag if necessary\n"
> > )
> > , command);
> > printf(_("Recognized sample formats are:")); @@ -429,6 +431,7 @@
> > enum {
> > OPT_USE_STRFTIME,
> > OPT_DUMP_HWPARAMS,
> > OPT_FATAL_ERRORS,
> > + OPT_NO_PERIOD_WAKEUP,
> > };
> >
> > /*
> > @@ -516,6 +519,7 @@ int main(int argc, char *argv[])
> > {"interactive", 0, 0, 'i'},
> > {"dump-hw-params", 0, 0, OPT_DUMP_HWPARAMS},
> > {"fatal-errors", 0, 0, OPT_FATAL_ERRORS},
> > + {"no-period-wakeup", 0, 0, OPT_NO_PERIOD_WAKEUP},
> > #ifdef CONFIG_SUPPORT_CHMAP
> > {"chmap", 1, 0, 'm'},
> > #endif
> > @@ -799,6 +803,9 @@ int main(int argc, char *argv[])
> > case OPT_FATAL_ERRORS:
> > fatal_errors = 1;
> > break;
> > + case OPT_NO_PERIOD_WAKEUP:
> > + no_period_wakeup = 1;
> > + break;
> > #ifdef CONFIG_SUPPORT_CHMAP
> > case 'm':
> > channel_map =
> snd_pcm_chmap_parse_string(optarg);
> > @@ -1396,6 +1403,12 @@ static void set_params(void)
> > &buffer_frames);
> > }
> > assert(err >= 0);
> > +
> > + if (no_period_wakeup) {
> > + err = snd_pcm_hw_params_set_period_wakeup(handle,
> params, 0);
> > + assert(err >= 0);
> > + }
> > +
> > monotonic = snd_pcm_hw_params_is_monotonic(params);
> > can_pause = snd_pcm_hw_params_can_pause(params);
> > err = snd_pcm_hw_params(handle, params);
> > --
> > 1.9.1
>
> As of v4.21-rc1, runtime of PCM substream can't run no_period_wakeup
> mode unless two conditions are satisfied[1]:
> - driver supports SNDRV_PCM_INFO_NO_PERIOD_WAKEUP
> - PCM applications set SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP
> flag to
> hardware parameter structure.
>
> Neither alsa-lib nor the most of existent userspace applications set
> SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP without explicit call of
> helper API. In this point, I can get your intention for this patch. If a driver
> just supports no_period_wakeup mode, such driver can't work well.
>
> However, such driver is problematic because apparently it can not run with
> many existent userspace applications and alsa-lib. Before applying this
> patch, we have enough discussion to prevent problems to introduce such
> problematic drivers into Linux sound subsystem, in my opinion.
What is helper API? I found that you have a similar function in axfer/xfer-libasound.c,
Which is disable_period_wakeup(). Do you think I need to porting this function to
Aplay?
Best regards
Wang shengjiu
>
> [1]
> https://emea01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit.
> kernel.org%2Fpub%2Fscm%2Flinux%2Fkernel%2Fgit%2Ftiwai%2Fsound.git%2
> Ftree%2Fsound%2Fcore%2Fpcm_native.c%3Fh%3Dsound-4.21-
> rc1%23n727&data=02%7C01%7Cshengjiu.wang%40nxp.com%7Cdaa8cb
> 93830245f7b27108d66b36fe91%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C
> 0%7C0%7C636814281289991663&sdata=Qv2Jfrd2qXc91gpwJhu28bhMC
> SJ5%2FgZJWDzP0gDT0Ws%3D&reserved=0
>
>
> Regards
>
> Takashi Sakamoto
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