From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Subhransu S. Prusty" Subject: Re: [PATCH 0/3] Add SPIB Support for Intel Skylake platforms Date: Tue, 30 Jan 2018 16:37:44 +0530 Message-ID: <20180130110743.GA26938@subhransu-desktop> References: <1517304986-16847-1-git-send-email-sriramx.periyasamy@intel.com> <013428a5-b593-1a7d-5a62-4e838a9fe5d0@sakamocchi.jp> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by alsa0.perex.cz (Postfix) with ESMTP id 20A532671F2 for ; Tue, 30 Jan 2018 12:23:18 +0100 (CET) Content-Disposition: inline In-Reply-To: <013428a5-b593-1a7d-5a62-4e838a9fe5d0@sakamocchi.jp> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org To: Takashi Sakamoto Cc: ALSA ML , Takashi Iwai , "Periyasamy, SriramX" , Patches Audio , Liam Girdwood , "Koul, Vinod" , Mark Brown List-Id: alsa-devel@alsa-project.org 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@alsa-project.org > http://mailman.alsa-project.org/mailman/listinfo/alsa-devel --