drm/bridge: imx8mp-hdmi-pai: enable PM runtime

There is an audio channel shift issue with multi channel case - the
channel order is correct for the first run, but the channel order is
shifted for the second run. The fix method is to reset the PAI interface
at the end of playback.

The reset can be handled by PM runtime, so enable PM runtime.

Fixes: 0205fae ("drm/bridge: imx: add driver for HDMI TX Parallel Audio Interface")
Signed-off-by: Shengjiu Wang <[email protected]>
Reviewed-by: Liu Ying <[email protected]>
Signed-off-by: Liu Ying <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: TE-N-ShengjiuWang

drivers/gpu/drm/bridge/imx/imx8mp-hdmi-pai.c

@@ -8,6 +8,7 @@
 #include <linux/module.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 #include <linux/regmap.h>
 #include <drm/bridge/dw_hdmi.h>
 #include <sound/asoundef.h>
@@ -33,6 +34,7 @@
 
 struct imx8mp_hdmi_pai {
 	struct regmap	*regmap;
+	struct device	*dev;
 };
 
 static void imx8mp_hdmi_pai_enable(struct dw_hdmi *dw_hdmi, int channel,
@@ -43,6 +45,9 @@ static void imx8mp_hdmi_pai_enable(struct dw_hdmi *dw_hdmi, int channel,
 	struct imx8mp_hdmi_pai *hdmi_pai = pdata->priv_audio;
 	int val;
 
+	if (pm_runtime_resume_and_get(hdmi_pai->dev) < 0)
+		return;
+
 	/* PAI set control extended */
 	val =  WTMK_HIGH(3) | WTMK_LOW(3);
 	val |= NUM_CH(channel);
@@ -85,6 +90,8 @@ static void imx8mp_hdmi_pai_disable(struct dw_hdmi *dw_hdmi)
 
 	/* Stop PAI */
 	regmap_write(hdmi_pai->regmap, HTX_PAI_CTRL, 0);
+
+	pm_runtime_put_sync(hdmi_pai->dev);
 }
 
 static const struct regmap_config imx8mp_hdmi_pai_regmap_config = {
@@ -101,6 +108,7 @@ static int imx8mp_hdmi_pai_bind(struct device *dev, struct device *master, void
 	struct imx8mp_hdmi_pai *hdmi_pai;
 	struct resource *res;
 	void __iomem *base;
+	int ret;
 
 	hdmi_pai = devm_kzalloc(dev, sizeof(*hdmi_pai), GFP_KERNEL);
 	if (!hdmi_pai)
@@ -121,6 +129,13 @@ static int imx8mp_hdmi_pai_bind(struct device *dev, struct device *master, void
 	plat_data->disable_audio = imx8mp_hdmi_pai_disable;
 	plat_data->priv_audio = hdmi_pai;
 
+	hdmi_pai->dev = dev;
+	ret = devm_pm_runtime_enable(dev);
+	if (ret < 0) {
+		dev_err(dev, "failed to enable PM runtime: %d\n", ret);
+		return ret;
+	}
+
 	return 0;
 }