[alsa-devel] ASoC: tegra: Does the PCM_TRIGGER_{PAUSE, RESUME} emulation really work?
Hi,
The tegra pcm driver tries to emulate SNDRV_PCM_TRIGGER_PAUSE and SNDRV_PCM_TRIGGER_RESUME. By passing SNDRV_PCM_TRIGGER_START and SNDRV_PCM_TRIGGER_STOP to snd_dmaengine_pcm_trigger. But does this really work? The old non-dmaengine based driver implemented this properly. I'd reset the dma position pointer for SNDRV_PCM_TRIGGER_START, but keep it where it was for SNDRV_PCM_TRIGGER_RESUME. But as far as I can see with the dmaengine based driver the pointer always gets reset to 0 for both SNDRV_PCM_TRIGGER_START and SNDRV_PCM_TRIGGER_RESUME.
- Lars
On 03/22/2013 10:26 AM, Lars-Peter Clausen wrote:
Hi,
The tegra pcm driver tries to emulate SNDRV_PCM_TRIGGER_PAUSE and SNDRV_PCM_TRIGGER_RESUME. By passing SNDRV_PCM_TRIGGER_START and SNDRV_PCM_TRIGGER_STOP to snd_dmaengine_pcm_trigger. But does this really work? The old non-dmaengine based driver implemented this properly. I'd reset the dma position pointer for SNDRV_PCM_TRIGGER_START, but keep it where it was for SNDRV_PCM_TRIGGER_RESUME. But as far as I can see with the dmaengine based driver the pointer always gets reset to 0 for both SNDRV_PCM_TRIGGER_START and SNDRV_PCM_TRIGGER_RESUME.
It's quite possible this hasn't been tested, or tested recently. I don't recall how to test PAUSE/RESUME. Can you enlighten me?
Laxman, can you comment here?
On 03/23/2013 12:35 AM, Stephen Warren wrote:
On 03/22/2013 10:26 AM, Lars-Peter Clausen wrote:
Hi,
The tegra pcm driver tries to emulate SNDRV_PCM_TRIGGER_PAUSE and SNDRV_PCM_TRIGGER_RESUME. By passing SNDRV_PCM_TRIGGER_START and SNDRV_PCM_TRIGGER_STOP to snd_dmaengine_pcm_trigger. But does this really work? The old non-dmaengine based driver implemented this properly. I'd reset the dma position pointer for SNDRV_PCM_TRIGGER_START, but keep it where it was for SNDRV_PCM_TRIGGER_RESUME. But as far as I can see with the dmaengine based driver the pointer always gets reset to 0 for both SNDRV_PCM_TRIGGER_START and SNDRV_PCM_TRIGGER_RESUME.
It's quite possible this hasn't been tested, or tested recently. I don't recall how to test PAUSE/RESUME. Can you enlighten me?
Hm, I don't know of an application that is specificity designed to test pause/resume, but any application using snd_pcm_pause, should be fine.
- Lars
participants (2)
-
Lars-Peter Clausen -
Stephen Warren