[PATCH 6/8] drm/bridge: dw-hdmi-i2s: reset audio fifo before applying new params

[Jerome Brunet]

When changing the audio hw params, reset the audio fifo to make sure
any old remaining data is flushed.

The databook mentions that such reset should be followed by a reset of
the i2s block to make sure the samples stay aligned

Cc: Jonas Karlman <jonas at kwiboo.se>
Signed-off-by: Jerome Brunet <jbrunet at baylibre.com>
---
 drivers/gpu/drm/bridge/synopsys/dw-hdmi-i2s-audio.c | 6 ++++--
 drivers/gpu/drm/bridge/synopsys/dw-hdmi.h           | 1 +
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-i2s-audio.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-i2s-audio.c
index 0864dee8d180..41bee0099578 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-i2s-audio.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-i2s-audio.c
@@ -49,6 +49,10 @@ static int dw_hdmi_i2s_hw_params(struct device *dev, void *data,
 		return -EINVAL;
 	}
 
+	/* Reset the FIFOs before applying new params */
+	hdmi_write(audio, HDMI_AUD_CONF0_SW_RESET, HDMI_AUD_CONF0);
+	hdmi_write(audio, (u8)~HDMI_MC_SWRSTZ_I2SSWRST_REQ, HDMI_MC_SWRSTZ);
+
 	inputclkfs	= HDMI_AUD_INPUTCLKFS_64FS;
 	conf0		= HDMI_AUD_CONF0_I2S_ALL_ENABLE;
 
@@ -102,8 +106,6 @@ static void dw_hdmi_i2s_audio_shutdown(struct device *dev, void *data)
 	struct dw_hdmi *hdmi = audio->hdmi;
 
 	dw_hdmi_audio_disable(hdmi);
-
-	hdmi_write(audio, HDMI_AUD_CONF0_SW_RESET, HDMI_AUD_CONF0);
 }
 
 static int dw_hdmi_i2s_get_dai_id(struct snd_soc_component *component,
diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.h b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.h
index 091d7c28aa17..a272fa393ae6 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.h
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.h
@@ -940,6 +940,7 @@ enum {
 	HDMI_MC_CLKDIS_PIXELCLK_DISABLE = 0x1,
 
 /* MC_SWRSTZ field values */
+	HDMI_MC_SWRSTZ_I2SSWRST_REQ = 0x08,
 	HDMI_MC_SWRSTZ_TMDSSWRST_REQ = 0x02,
 
 /* MC_FLOWCTRL field values */
-- 
2.21.0