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From:   Olivier Moysan <olivier.moysan@st.com>
To:     <lgirdwood@gmail.com>, <broonie@kernel.org>, <perex@perex.cz>,
        <tiwai@suse.com>, <mcoquelin.stm32@gmail.com>,
        <alexandre.torgue@st.com>, <alsa-devel@alsa-project.org>,
        <linux-arm-kernel@lists.infradead.org>,
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        <linux-kernel@vger.kernel.org>, <olivier.moysan@st.com>,
        <arnaud.pouliquen@st.com>, <benjamin.gaignard@st.com>
Subject: [PATCH 7/7] ASoC: stm32: i2s: skip useless write in slave mode
Date:   Tue, 26 Feb 2019 14:51:10 +0100
Message-ID: <1551189070-15469-8-git-send-email-olivier.moysan@st.com>
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Dummy write in capture master mode is used to gate
bus clocks. This write is useless in slave mode
as the clocks are not managed by slave.

Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
---
 sound/soc/stm/stm32_i2s.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/soc/stm/stm32_i2s.c b/sound/soc/stm/stm32_i2s.c
index 42ce87a35104..47c334de6b09 100644
--- a/sound/soc/stm/stm32_i2s.c
+++ b/sound/soc/stm/stm32_i2s.c
@@ -623,8 +623,8 @@ static int stm32_i2s_trigger(struct snd_pcm_substream *substream, int cmd,
 		} else {
 			ier = I2S_IER_OVRIE;
 
-			if (i2s->refcount == 1)
-				/* dummy write to trigger capture */
+			if (STM32_I2S_IS_MASTER(i2s) && i2s->refcount == 1)
+				/* dummy write to gate bus clocks */
 				regmap_write(i2s->regmap,
 					     STM32_I2S_TXDR_REG, 0);
 		}
-- 
2.7.4