[PATCH v3 15/24] 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.

The interrupt number may be defined either in the DT or at encoder set
config time for non-DT boards.

Signed-off-by: Jean-Francois Moine <moinejf@free.fr>
---
v3
    - remarks from Russell King
	- move the setting of the wq_edid_wait flag before asking the
	  device to read the EDID
	  Thanks about this bug fix, but I don't see the other problem:
	  there is no reason for the read_edid_block function to be
	  called more than once...
	- use '0' as 'no irq'
	- remove the useless delay after irq init
---
 drivers/gpu/drm/i2c/tda998x_drv.c | 126 +++++++++++++++++++++++++++++++++-----
 include/drm/i2c/tda998x.h         |   2 +
 2 files changed, 114 insertions(+), 14 deletions(-)

diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c
index 98142db..013a67c 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_format;
 	u8 audio_frame[6];
 	u32 audio_port;
+
+	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)
@@ -528,6 +539,62 @@ 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_DRIVER(
+		"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 void tda_irq_init(struct tda998x_priv *priv)
+{
+	int ret;
+
+	/* init read EDID waitqueue */
+	init_waitqueue_head(&priv->wq_edid);
+
+	/* 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->irq, NULL,
+				   tda998x_irq_thread,
+				   IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+				   "tda998x", priv);
+	if (ret) {
+		dev_err(&priv->hdmi->dev, "failed to request IRQ#%u: %d\n",
+			priv->irq, ret);
+		return;
+	}
+
+	/* enable HPD irq */
+	cec_write(priv, REG_CEC_RXSHPDINTENA,
+			CEC_RXSHPDLEV_HPD | CEC_RXSHPDLEV_RXSENS);
+}
+
 static uint8_t tda998x_cksum(uint8_t *buf, size_t bytes)
 {
 	uint8_t sum = 0;
@@ -720,6 +787,10 @@ tda998x_encoder_set_config(struct drm_encoder *encoder, void *params)
 		priv->audio_port = p->audio_cfg;
 		priv->audio_format = p->audio_format;
 	}
+
+	priv->irq = p->irq;
+	if (p->irq)
+		tda_irq_init(priv);
 }
 
 static void
@@ -990,9 +1061,6 @@ read_edid_block(struct drm_encoder *encoder, uint8_t *buf, int blk)
 	uint8_t offset, segptr;
 	int ret, i;
 
-	/* enable EDID read irq: */
-	reg_set(priv, REG_INT_FLAGS_2, INT_FLAGS_2_EDID_BLK_RD);
-
 	offset = (blk & 1) ? 128 : 0;
 	segptr = blk / 2;
 
@@ -1002,23 +1070,36 @@ read_edid_block(struct drm_encoder *encoder, uint8_t *buf, int blk)
 	reg_write(priv, REG_DDC_SEGM, segptr);
 
 	/* enable reading EDID: */
+	priv->wq_edid_wait = 1;
 	reg_write(priv, REG_EDID_CTRL, 0x1);
 
 	/* flag must be cleared by sw: */
 	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->irq != 0) {
+		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) {
@@ -1027,8 +1108,6 @@ 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;
 }
 
@@ -1046,6 +1125,9 @@ do_get_edid(struct drm_encoder *encoder)
 	if (priv->rev == TDA19988)
 		reg_clear(priv, REG_TX4, TX4_PD_RAM);
 
+	/* enable EDID read irq: */
+	reg_set(priv, REG_INT_FLAGS_2, INT_FLAGS_2_EDID_BLK_RD);
+
 	/* base block fetch */
 	if (read_edid_block(encoder, block, 0))
 		goto fail;
@@ -1118,7 +1200,13 @@ static int
 tda998x_encoder_create_resources(struct drm_encoder *encoder,
 				struct drm_connector *connector)
 {
-	DBG("");
+	struct tda998x_priv *priv = to_tda998x_priv(encoder);
+
+	if (priv->irq != 0)
+		connector->polled = DRM_CONNECTOR_POLL_HPD;
+	else
+		connector->polled = DRM_CONNECTOR_POLL_CONNECT |
+			DRM_CONNECTOR_POLL_DISCONNECT;
 	return 0;
 }
 
@@ -1137,6 +1225,8 @@ tda998x_encoder_destroy(struct drm_encoder *encoder)
 {
 	struct tda998x_priv *priv = to_tda998x_priv(encoder);
 	drm_i2c_encoder_destroy(encoder);
+	if (priv->irq != 0)
+		free_irq(priv->irq, priv);
 	if (priv->cec)
 		i2c_unregister_device(priv->cec);
 	kfree(priv);
@@ -1195,6 +1285,7 @@ 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;
@@ -1259,6 +1350,13 @@ tda998x_encoder_init(struct i2c_client *client,
 		priv->vip_cntrl_2 = video;
 	}
 
+	/* install the optional HDMI connect IRQ */
+	priv->irq = irq_of_parse_and_map(np, 0);
+	if (priv->irq < 0)
+		priv->irq = 0;
+	if (priv->irq != 0)
+		tda_irq_init(priv);
+
 	return 0;
 
 fail:
diff --git a/include/drm/i2c/tda998x.h b/include/drm/i2c/tda998x.h
index d469b07..8dc2982 100644
--- a/include/drm/i2c/tda998x.h
+++ b/include/drm/i2c/tda998x.h
@@ -25,6 +25,8 @@ struct tda998x_encoder_params {
 	} audio_format;
 
 	unsigned audio_sample_rate;
+
+	int irq;
 };
 
 #endif
-- 
1.8.5.3