[PATCH v2 13/28] drm/i2c: tda998x: use irq for connection status and EDID read

[moinejf@free.fr (Jean-Francois Moine)]

This patch adds the optional treatment of the tda998x IRQ.

The interrupt function is used to know the display connection status
without polling and to speedup reading the EDID.

Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
---
 drivers/gpu/drm/i2c/tda998x_drv.c            | 116 +++++++++++++++++++--
 .../devicetree/bindings/drm/i2c/tda998x.txt  |   3 +++
 2 file changed, 108 insertions(+), 11 deletions(-)

diff --git a/Documentation/devicetree/bindings/drm/i2c/tda998x.txt b/Documentation/devicetree/bindings/drm/i2c/tda998x.txt
index f07339e1..83d7880 100644
--- a/Documentation/devicetree/bindings/drm/i2c/tda998x.txt
+++ b/Documentation/devicetree/bindings/drm/i2c/tda998x.txt
@@ -4,6 +4,7 @@ Required properties;
   - compatible: must be "nxp,tda998x"
 
 Optional properties:
+  - interrupts: interrupt number for HDMI exchanges - default: by polling
   - video-ports: 24 bits value - default: <0x230145>
 
 Example:
@@ -11,6 +12,8 @@ Example:
 	tda998x: hdmi-encoder {
 		compatible = "nxp,tda998x";
 		reg = <0x70>;
+		interrupt-parent = <&gpio0>;
+		interrupts = <27 2>;		/* falling edge */
 		pinctrl-0 = <&pmx_camera>;
 		pinctrl-names = "default";
 	};
diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c
index b87802f..2187d63 100644
--- a/drivers/gpu/drm/i2c/tda998x_drv.c
+++ b/drivers/gpu/drm/i2c/tda998x_drv.c
@@ -19,6 +19,7 @@
 
 #include <linux/hdmi.h>
 #include <linux/module.h>
+#include <linux/of_irq.h>
 
 #include <drm/drmP.h>
 #include <drm/drm_crtc_helper.h>
@@ -44,6 +45,11 @@ struct tda998x_priv {
 	u8 audio_type;		/* audio type */
 	u8 audio_frame[6];
 	u32 audio_port;
+
+	int int_irq;
+	wait_queue_head_t wq_edid;
+	volatile int wq_edid_wait;
+	struct drm_encoder *encoder;
 };
 
 #define to_tda998x_priv(x)  ((struct tda998x_priv *)to_encoder_slave(x)->slave_priv)
@@ -310,11 +316,16 @@ struct tda998x_priv {
 
 /* CEC registers: (not paged)
  */
+#define REG_CEC_INTSTATUS         0xee                /* read */
+# define CEC_INTSTATUS_CEC        (1 << 0)
+# define CEC_INTSTATUS_HDMI       (1 << 1)
 #define REG_CEC_FRO_IM_CLK_CTRL   0xfb                /* read/write */
 # define CEC_FRO_IM_CLK_CTRL_GHOST_DIS (1 << 7)
 # define CEC_FRO_IM_CLK_CTRL_ENA_OTP   (1 << 6)
 # define CEC_FRO_IM_CLK_CTRL_IMCLK_SEL (1 << 1)
 # define CEC_FRO_IM_CLK_CTRL_FRO_DIV   (1 << 0)
+#define REG_CEC_RXSHPDINTENA      0xfc                /* read/write */
+#define REG_CEC_RXSHPDINT         0xfd                /* read */
 #define REG_CEC_RXSHPDLEV         0xfe                /* read */
 # define CEC_RXSHPDLEV_RXSENS     (1 << 0)
 # define CEC_RXSHPDLEV_HPD        (1 << 1)
@@ -520,6 +531,34 @@ tda998x_reset(struct tda998x_priv *priv)
 	reg_write(priv, REG_MUX_VP_VIP_OUT, 0x24);
 }
 
+/*
+ * only 2 interrupts may occur: screen plug/unplug and EDID read
+ */
+static irqreturn_t tda998x_irq_thread(int irq, void *data)
+{
+	struct tda998x_priv *priv = data;
+	u8 sta, cec, lvl, flag0, flag1, flag2;
+
+	if (!priv)
+		return IRQ_HANDLED;
+	sta = cec_read(priv, REG_CEC_INTSTATUS);
+	cec = cec_read(priv, REG_CEC_RXSHPDINT);
+	lvl = cec_read(priv, REG_CEC_RXSHPDLEV);
+	flag0 = reg_read(priv, REG_INT_FLAGS_0);
+	flag1 = reg_read(priv, REG_INT_FLAGS_1);
+	flag2 = reg_read(priv, REG_INT_FLAGS_2);
+	DRM_DEBUG("tda irq sta %02x cec %02x lvl %02x f0 %02x f1 %02x f2 %02x\n",
+			sta, cec, lvl, flag0, flag1, flag2);
+	if ((flag2 & INT_FLAGS_2_EDID_BLK_RD) && priv->wq_edid_wait) {
+		priv->wq_edid_wait = 0;
+		wake_up(&priv->wq_edid);
+	} else if (cec != 0) {			/* level change */
+		if (priv->encoder && priv->encoder->dev)
+			drm_helper_hpd_irq_event(priv->encoder->dev);
+	}
+	return IRQ_HANDLED;
+}
+
 static uint8_t tda998x_cksum(uint8_t *buf, size_t bytes)
 {
 	uint8_t sum = 0;
@@ -982,7 +1021,8 @@ read_edid_block(struct drm_encoder *encoder, uint8_t *buf, int blk)
 	int ret, i;
 
 	/* enable EDID read irq: */
-	reg_set(priv, REG_INT_FLAGS_2, INT_FLAGS_2_EDID_BLK_RD);
+	if (blk == 0)
+		reg_set(priv, REG_INT_FLAGS_2, INT_FLAGS_2_EDID_BLK_RD);
 
 	offset = (blk & 1) ? 128 : 0;
 	segptr = blk / 2;
@@ -999,17 +1039,30 @@ read_edid_block(struct drm_encoder *encoder, uint8_t *buf, int blk)
 	reg_write(priv, REG_EDID_CTRL, 0x0);
 
 	/* wait for block read to complete: */
-	for (i = 100; i > 0; i--) {
-		ret = reg_read(priv, REG_INT_FLAGS_2);
-		if (ret < 0)
-			return ret;
-		if (ret & INT_FLAGS_2_EDID_BLK_RD)
-			break;
-		msleep(1);
+	if (priv->int_irq != NO_IRQ) {
+		priv->wq_edid_wait = 1;
+		i = wait_event_timeout(priv->wq_edid,
+					!priv->wq_edid_wait,
+					msecs_to_jiffies(100));
+		if (i < 0) {
+			dev_err(encoder->dev->dev, "read edid wait err %d\n", i);
+			return i;
+		}
+	} else {
+		for (i = 10; i > 0; i--) {
+			msleep(10);
+			ret = reg_read(priv, REG_INT_FLAGS_2);
+			if (ret < 0)
+				return ret;
+			if (ret & INT_FLAGS_2_EDID_BLK_RD)
+				break;
+		}
 	}
 
-	if (i == 0)
+	if (i == 0) {
+		dev_err(encoder->dev->dev, "read edid timeout\n");
 		return -ETIMEDOUT;
+	}
 
 	ret = reg_read_range(priv, REG_EDID_DATA_0, buf, EDID_LENGTH);
 	if (ret != EDID_LENGTH) {
@@ -1018,8 +1071,6 @@ read_edid_block(struct drm_encoder *encoder, uint8_t *buf, int blk)
 		return ret;
 	}
 
-	reg_clear(priv, REG_INT_FLAGS_2, INT_FLAGS_2_EDID_BLK_RD);
-
 	return 0;
 }
 
@@ -1109,7 +1160,14 @@ static int
 tda998x_encoder_create_resources(struct drm_encoder *encoder,
 				struct drm_connector *connector)
 {
+	struct tda998x_priv *priv = to_tda998x_priv(encoder);
+
 	DBG("");
+	if (priv->int_irq != NO_IRQ)
+		connector->polled = DRM_CONNECTOR_POLL_HPD;
+	else
+		connector->polled = DRM_CONNECTOR_POLL_CONNECT |
+			DRM_CONNECTOR_POLL_DISCONNECT;
 	return 0;
 }
 
@@ -1128,6 +1186,8 @@ tda998x_encoder_destroy(struct drm_encoder *encoder)
 {
 	struct tda998x_priv *priv = to_tda998x_priv(encoder);
 	drm_i2c_encoder_destroy(encoder);
+	if (priv->int_irq != NO_IRQ)
+		free_irq(priv->int_irq, priv);
 	if (priv->cec)
 		i2c_unregister_device(priv->cec);
 	kfree(priv);
@@ -1186,6 +1246,7 @@ tda998x_encoder_init(struct i2c_client *client,
 	priv->cec = i2c_new_dummy(client->adapter, 0x34);
 	if (!priv->cec)
 		return -ENODEV;
+	priv->encoder = &encoder_slave->base;
 	priv->dpms = DRM_MODE_DPMS_OFF;
 
 	encoder_slave->slave_priv = priv;
@@ -1250,6 +1311,39 @@ tda998x_encoder_init(struct i2c_client *client,
 		priv->vip_cntrl_2 = video;
 	}
 
+	/* install the optional HDMI connect IRQ */
+	priv->int_irq = irq_of_parse_and_map(np, 0);
+	if (priv->int_irq < 0)
+		priv->int_irq = NO_IRQ;
+	if (priv->int_irq != NO_IRQ) {
+
+		/* init read EDID waitqueue */
+		init_waitqueue_head(&priv->wq_edid);
+/*		priv->wq_edid_wait = 0;	*/
+
+		/* clear pending interrupts */
+		reg_read(priv, REG_INT_FLAGS_0);
+		reg_read(priv, REG_INT_FLAGS_1);
+		reg_read(priv, REG_INT_FLAGS_2);
+
+		ret = request_threaded_irq(priv->int_irq, NULL,
+					   tda998x_irq_thread,
+					   IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+					   "tda998x-int", priv);
+		if (ret) {
+			dev_err(&client->dev, "failed to request IRQ#%u: %d\n",
+				priv->int_irq, ret);
+			goto fail;
+		}
+
+		/* enable HPD irq */
+		cec_write(priv, REG_CEC_RXSHPDINTENA,
+				CEC_RXSHPDLEV_HPD | CEC_RXSHPDLEV_RXSENS);
+
+		/* treat the first irq if any */
+		msleep(10);
+	}
+
 	return 0;
 
 fail:
-- 
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