[Intel-gfx] [PATCH 7/7] ALSA: x86: hdmi: continue playback even when display resolution changes
Takashi Iwai
tiwai at suse.de
Wed Dec 14 13:01:05 UTC 2016
On Mon, 12 Dec 2016 19:10:43 +0100,
Jerome Anand wrote:
>
> When the display resolution changes, the drm disables the
> display pipes due to which audio rendering stops. At this
> time, we need to ensure the existing audio pointers and
> buffers are cleared out so that the playback can restarted
> once the display pipe is enabled with a different N/CTS values
>
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
> Signed-off-by: Jerome Anand <jerome.anand at intel.com>
> ---
> sound/x86/intel_hdmi_audio.c | 21 ++++++++++++++++++---
> 1 file changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/sound/x86/intel_hdmi_audio.c b/sound/x86/intel_hdmi_audio.c
> index 9249521..d6fd638 100644
> --- a/sound/x86/intel_hdmi_audio.c
> +++ b/sound/x86/intel_hdmi_audio.c
> @@ -43,6 +43,7 @@ static DEFINE_MUTEX(had_mutex);
> static int hdmi_card_index = SNDRV_DEFAULT_IDX1;
> static char *hdmi_card_id = SNDRV_DEFAULT_STR1;
> static struct snd_intelhad *had_data;
> +static int underrun_count;
>
> module_param(hdmi_card_index, int, 0444);
> MODULE_PARM_DESC(hdmi_card_index,
> @@ -1114,6 +1115,7 @@ static int snd_intelhad_open(struct snd_pcm_substream *substream)
> intelhaddata = snd_pcm_substream_chip(substream);
> had_stream = intelhaddata->private_data;
> runtime = substream->runtime;
> + underrun_count = 0;
>
> pm_runtime_get(intelhaddata->dev);
>
> @@ -1506,10 +1508,23 @@ static snd_pcm_uframes_t snd_intelhad_pcm_pointer(
>
> buf_id = intelhaddata->curr_buf % 4;
> had_read_register(AUD_BUF_A_LENGTH + (buf_id * HAD_REG_WIDTH), &t);
> - if (t == 0) {
> - pr_debug("discovered buffer done for buf %d\n", buf_id);
> - /* had_process_buffer_done(intelhaddata); */
> +
> + if ((t == 0) || (t == ((u32)-1L))) {
> + underrun_count++;
> + pr_debug("discovered buffer done for buf %d, count = %d\n",
> + buf_id, underrun_count);
> +
> + if (underrun_count > (HAD_MIN_PERIODS/2)) {
> + pr_debug("assume audio_codec_reset, underrun = %d - do xrun\n",
> + underrun_count);
> + underrun_count = 0;
> + return SNDRV_PCM_POS_XRUN;
> + }
> + } else {
> + /* Reset Counter */
> + underrun_count = 0;
> }
> +
> t = intelhaddata->buf_info[buf_id].buf_size - t;
>
> if (intelhaddata->stream_info.buffer_rendered)
This change itself is OK, but this made me wonder about the driver
implementation: the current MAX_PB=1 is the hardware limitation or the
soft limitation? That is, can't we play back two streams when we
connect two HDMI monitors?
thanks,
Takashi
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