linux-kernel - [PATCH v2 6/8] drm/bridge: dw-hdmi-i2s: reset audio fifo before applying new params

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Date:   Mon, 12 Aug 2019 14:07:24 +0200
From:   Jerome Brunet <jbrunet@...libre.com>
To:     Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>
Cc:     Jerome Brunet <jbrunet@...libre.com>,
        Kevin Hilman <khilman@...libre.com>,
        Jonas Karlman <jonas@...boo.se>,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH v2 6/8] drm/bridge: dw-hdmi-i2s: reset audio fifo before applying new params

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

Reviewed-by: Jonas Karlman <jonas@...boo.se>
Signed-off-by: Jerome Brunet <jbrunet@...libre.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