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.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound.git/tree/sound/core/pcm_native.c?h=sound-4.21-rc1#n727
Regards
Takashi Sakamoto
_______________________________________________
Alsa-devel mailing list
Alsa-devel@xxxxxxxxxxxxxxxx
http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
