From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sriram Periyasamy Subject: [RESEND][PATCH v4 1/3] ALSA: core: let low-level driver or userspace disable rewinds Date: Tue, 20 Mar 2018 21:31:06 +0530 Message-ID: <1521561668-28613-2-git-send-email-sriramx.periyasamy@intel.com> References: <1521561668-28613-1-git-send-email-sriramx.periyasamy@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by alsa0.perex.cz (Postfix) with ESMTP id 7EDB926720A for ; Tue, 20 Mar 2018 17:09:35 +0100 (CET) In-Reply-To: <1521561668-28613-1-git-send-email-sriramx.periyasamy@intel.com> 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: ALSA ML , Mark Brown Cc: Takashi Iwai , Sriram Periyasamy , Pierre-Louis Bossart , Ramesh Babu , Takashi Sakamoto , Liam Girdwood , Patches Audio , Vinod Koul , "Subhransu S . Prusty" List-Id: alsa-devel@alsa-project.org From: Pierre-Louis Bossart Add new hw_params flag to explicitly tell driver that rewinds will never be used. This can be used by low-level driver to optimize DMA operations and reduce power consumption. Use this flag only when data written in ring buffer will never be invalidated, e.g. any update of appl_ptr is final. Note that the update of appl_ptr include both a read/write data operation as well as snd_pcm_forward() whose behavior is not modified. Signed-off-by: Pierre-Louis Bossart Signed-off-by: Ramesh Babu Signed-off-by: Subhransu S. Prusty Signed-off-by: Sriram Periyasamy --- include/sound/pcm.h | 1 + include/uapi/sound/asound.h | 1 + sound/core/pcm_native.c | 8 ++++++++ 3 files changed, 10 insertions(+) diff --git a/include/sound/pcm.h b/include/sound/pcm.h index e054c583d3b3..f60397eb4aab 100644 --- a/include/sound/pcm.h +++ b/include/sound/pcm.h @@ -379,6 +379,7 @@ struct snd_pcm_runtime { unsigned int rate_num; unsigned int rate_den; unsigned int no_period_wakeup: 1; + unsigned int no_rewinds:1; /* -- SW params -- */ int tstamp_mode; /* mmap timestamp is updated */ diff --git a/include/uapi/sound/asound.h b/include/uapi/sound/asound.h index ed0a120d4f08..ff57e4c89de4 100644 --- a/include/uapi/sound/asound.h +++ b/include/uapi/sound/asound.h @@ -377,6 +377,7 @@ typedef int snd_pcm_hw_param_t; #define SNDRV_PCM_HW_PARAMS_NORESAMPLE (1<<0) /* avoid rate resampling */ #define SNDRV_PCM_HW_PARAMS_EXPORT_BUFFER (1<<1) /* export buffer */ #define SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP (1<<2) /* disable period wakeups */ +#define SNDRV_PCM_HW_PARAMS_NO_REWINDS (1<<3) /* disable rewinds */ struct snd_interval { unsigned int min, max; diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c index 77ba50ddcf9e..4616420cdbf7 100644 --- a/sound/core/pcm_native.c +++ b/sound/core/pcm_native.c @@ -692,6 +692,8 @@ static int snd_pcm_hw_params(struct snd_pcm_substream *substream, runtime->no_period_wakeup = (params->info & SNDRV_PCM_INFO_NO_PERIOD_WAKEUP) && (params->flags & SNDRV_PCM_HW_PARAMS_NO_PERIOD_WAKEUP); + runtime->no_rewinds = + (params->flags & SNDRV_PCM_HW_PARAMS_NO_REWINDS) ? 1 : 0; bits = snd_pcm_format_physical_width(runtime->format); runtime->sample_bits = bits; @@ -2614,6 +2616,9 @@ static snd_pcm_sframes_t snd_pcm_playback_rewind(struct snd_pcm_substream *subst if (frames == 0) return 0; + if (runtime->no_rewinds) + return -ENODEV; + snd_pcm_stream_lock_irq(substream); ret = do_pcm_hwsync(substream); if (!ret) @@ -2632,6 +2637,9 @@ static snd_pcm_sframes_t snd_pcm_capture_rewind(struct snd_pcm_substream *substr if (frames == 0) return 0; + if (runtime->no_rewinds) + return -ENODEV; + snd_pcm_stream_lock_irq(substream); ret = do_pcm_hwsync(substream); if (!ret) -- 2.7.4