[PATCH 3/8] ASoC: SOF: pcm: add mechanisms to disable ALSA pause_push/release - Pierre-Louis Bossart

From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
To: alsa-devel@alsa-project.org
Cc: tiwai@suse.de, broonie@kernel.org,
	Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>,
	Kai Vehmanen <kai.vehmanen@linux.intel.com>,
	Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Subject: [PATCH 3/8] ASoC: SOF: pcm: add mechanisms to disable ALSA pause_push/release
Date: Thu, 10 Jun 2021 15:53:21 -0500	[thread overview]
Message-ID: <20210610205326.1176400-4-pierre-louis.bossart@linux.intel.com> (raw)
In-Reply-To: <20210610205326.1176400-1-pierre-louis.bossart@linux.intel.com>

PulseAudio, PipeWire and CRAS do not use pause push/release, which
means that we can optionally disable this capability without any
impact on most users.

In addition, on some platforms, e.g. based on HDaudio DMAs, support for
pause_push/release prevents the system from entering low-power
states.

This patch suggests an opt-in selection via kconfig or kernel
parameter to disable pause.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
---
 sound/soc/sof/Kconfig | 9 +++++++++
 sound/soc/sof/pcm.c   | 7 +++++++
 2 files changed, 16 insertions(+)

diff --git a/sound/soc/sof/Kconfig b/sound/soc/sof/Kconfig
index cd659493b5df..81b834558a2d 100644
--- a/sound/soc/sof/Kconfig
+++ b/sound/soc/sof/Kconfig
@@ -55,6 +55,15 @@ config SND_SOC_SOF_DEBUG_PROBES
 	  Say Y if you want to enable probes.
 	  If unsure, select "N".
 
+config SND_SOC_SOF_PCM_DISABLE_PAUSE
+	bool "SOF disable pause push/release"
+	help
+	  This option disables ALSA pause push/release capabilities for
+	  SOF drivers. These capabilities are not used by typical
+	  sound servers such as PulseAudio, PipeWire and CRAS.
+	  Say Y if you want to disable pause push/release
+	  If unsure, select "N".
+
 config SND_SOC_SOF_DEVELOPER_SUPPORT
 	bool "SOF developer options support"
 	depends on EXPERT
diff --git a/sound/soc/sof/pcm.c b/sound/soc/sof/pcm.c
index 9893b182da43..bab837ed8c7f 100644
--- a/sound/soc/sof/pcm.c
+++ b/sound/soc/sof/pcm.c
@@ -10,6 +10,7 @@
 // PCM Layer, interface between ALSA and IPC.
 //
 
+#include <linux/moduleparam.h>
 #include <linux/pm_runtime.h>
 #include <sound/pcm_params.h>
 #include <sound/sof.h>
@@ -20,6 +21,10 @@
 #include "compress.h"
 #endif
 
+static bool pcm_disable_pause = IS_ENABLED(CONFIG_SND_SOC_SOF_PCM_DISABLE_PAUSE);
+module_param_named(disable_pause, pcm_disable_pause, bool, 0444);
+MODULE_PARM_DESC(disable_pause, "SOF HDA disable pause");
+
 /* Create DMA buffer page table for DSP */
 static int create_page_table(struct snd_soc_component *component,
 			     struct snd_pcm_substream *substream,
@@ -480,6 +485,8 @@ static int sof_pcm_open(struct snd_soc_component *component,
 
 	/* set runtime config */
 	runtime->hw.info = ops->hw_info; /* platform-specific */
+	if (pcm_disable_pause)
+		runtime->hw.info &= ~SNDRV_PCM_INFO_PAUSE;
 
 	/* set any runtime constraints based on topology */
 	runtime->hw.formats = le64_to_cpu(caps->formats);
-- 
2.25.1

