On Tue, Jan 30, 2018 at 04:08:39PM +0530, Takashi Sakamoto wrote: > Hi, > > On Jan 30 2018 18:36, Sriram Periyasamy wrote: > > Skylake audio controller supports SPIB (Software Position in buffer) > > capability, which can be used to inform position of application pointer > > to host DMA controller. When SPIB mode is enabled, driver could write > > the application pointer position in SPIB register. Host DMA will make > > sure it won't read/write beyond bytes specified in SPIB register. > > > > SPIB mode will be useful in low power use cases, where DSP could > > pre-fetch large buffers to avoid frequent wakes caused due to interrupts. > > > > To support SPIB in the driver, save the spib values in stream context > > which can be restored during resume from S3. Add new hw_params flag to > > explicitly tell driver that rewinds will never be used. > > > > Pierre-Louis Bossart (1): > > ALSA: core: let low-level driver or userspace disable rewinds > > > > Ramesh Babu (2): > > ALSA: hda: ext: add spib to stream context > > ASoC: Intel: Skylake: Add support for spib mode > > > > include/sound/hdaudio_ext.h | 1 + > > include/sound/pcm.h | 1 + > > include/uapi/sound/asound.h | 1 + > > sound/core/pcm_native.c | 8 ++++++++ > > sound/hda/ext/hdac_ext_stream.c | 2 ++ > > sound/soc/intel/skylake/skl-pcm.c | 43 ++++++++++++++++++++++++++++++++++++++- > > 6 files changed, 55 insertions(+), 1 deletion(-) > > In my opinion, when drivers > return appropriate values at implementations of > "struct snd_pcm_ops.pointer" and "struct snd_pcm_ops.ack", your aim is > satisfied. In short, you can let ALSA PCM core to handle > rewinding/forwarding requests from userland for zero number of handled > frames in result. So the 'SNDRV_PCM_HW_PARAMS_NO_REWINDS' flag is > useless. Based on the earlier discussion in v3, this series includes the usage of the 'SNDRV_PCM_HW_PARAMS_NO_REWINDS' flag. Please refer to the discussion on https://patchwork.kernel.org/patch/9795233/ > > From me, please refer to our previous discussion about this > flag[1][2][3], then describe your insistence of this flag. At least, > it's not better idea to abandon the old discussion when posting this > kind of patches. Additionally you should add 'v4' in title of this Yes should have added the reference and v4. Sorry to have missed it. Regards, Subhransu > patchset to represent this patchset is a part of series of your work for > the flag and your Intel platform. > > [1] > http://mailman.alsa-project.org/pipermail/alsa-devel/2017-May/120676.html > [2] > http://mailman.alsa-project.org/pipermail/alsa-devel/2017-June/121683.html > [3] > http://mailman.alsa-project.org/pipermail/alsa-devel/2017-June/121967.html > > > Regards > > Takashi Sakamoto > _______________________________________________ > Alsa-devel mailing list > Alsa-devel@xxxxxxxxxxxxxxxx > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel -- _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel