From 5e7820e369248f880767c4c4079b414529bc2125 Mon Sep 17 00:00:00 2001
From: Brent Lu <brent.lu@intel.com>
Date: Fri, 31 Jul 2020 20:26:04 +0800
Subject: [PATCH] ASoC: intel: atom: Add period size constraint
Git-commit: 5e7820e369248f880767c4c4079b414529bc2125
Patch-mainline: v5.9-rc6
References: jsc#SLE-16518

Use constraint to make sure the period size could always be multiple
of 1ms to align with the fundamental design/limitation of firmware.

Signed-off-by: Brent Lu <brent.lu@intel.com>
Link: https://lore.kernel.org/r/1596198365-10105-2-git-send-email-brent.lu@intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 sound/soc/intel/atom/sst-mfld-platform-pcm.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/sound/soc/intel/atom/sst-mfld-platform-pcm.c b/sound/soc/intel/atom/sst-mfld-platform-pcm.c
index b1cac7abdc0a..fba2c795ce0d 100644
--- a/sound/soc/intel/atom/sst-mfld-platform-pcm.c
+++ b/sound/soc/intel/atom/sst-mfld-platform-pcm.c
@@ -333,6 +333,17 @@ static int sst_media_open(struct snd_pcm_substream *substream,
 	if (ret_val < 0)
 		goto out_power_up;
 
+	/*
+	 * Make sure the period to be multiple of 1ms to align the
+	 * design of firmware. Apply same rule to buffer size to make
+	 * sure alsa could always find a value for period size
+	 * regardless the buffer size given by user space.
+	 */
+	snd_pcm_hw_constraint_step(substream->runtime, 0,
+			   SNDRV_PCM_HW_PARAM_PERIOD_SIZE, 48);
+	snd_pcm_hw_constraint_step(substream->runtime, 0,
+			   SNDRV_PCM_HW_PARAM_BUFFER_SIZE, 48);
+
 	/* Make sure, that the period size is always even */
 	snd_pcm_hw_constraint_step(substream->runtime, 0,
 			   SNDRV_PCM_HW_PARAM_PERIODS, 2);
-- 
2.16.4