[PATCH v4 1/1] drm/bridge: it6505: fix hibernate to resume no display issue

[kuro <kuro.chung@ite.com.tw>]

From: Kuro <kuro.chung@ite.com.tw>

ITE added a FIFO reset bit for input video. When system power resume,
the TTL input of it6505 may get some noise before video signal stable
and the hardware function reset is required.
But the input FIFO reset will also trigger error interrupts of output module rising.
Thus, it6505 have to wait a period can clear those expected error interrupts
caused by manual hardware reset in one interrupt handler calling to avoid interrupt looping.

Signed-off-by: Kuro Chung <kuro.chung@ite.corp-partner.google.com>

---
 drivers/gpu/drm/bridge/ite-it6505.c | 50 ++++++++++++++++++++---------
 1 file changed, 35 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/bridge/ite-it6505.c b/drivers/gpu/drm/bridge/ite-it6505.c
index b53da9bb65a16..eff888fe7c2e7 100644
--- a/drivers/gpu/drm/bridge/ite-it6505.c
+++ b/drivers/gpu/drm/bridge/ite-it6505.c
@@ -1318,6 +1318,8 @@ static void it6505_video_reset(struct it6505 *it6505)
 	it6505_set_bits(it6505, REG_DATA_MUTE_CTRL, EN_VID_MUTE, EN_VID_MUTE);
 	it6505_set_bits(it6505, REG_INFOFRAME_CTRL, EN_VID_CTRL_PKT, 0x00);
 	it6505_set_bits(it6505, REG_RESET_CTRL, VIDEO_RESET, VIDEO_RESET);
+	it6505_set_bits(it6505, REG_VID_BUS_CTRL1, TX_FIFO_RESET, 0x02);
+	it6505_set_bits(it6505, REG_VID_BUS_CTRL1, TX_FIFO_RESET, 0x00);
 	it6505_set_bits(it6505, REG_501_FIFO_CTRL, RST_501_FIFO, RST_501_FIFO);
 	it6505_set_bits(it6505, REG_501_FIFO_CTRL, RST_501_FIFO, 0x00);
 	it6505_set_bits(it6505, REG_RESET_CTRL, VIDEO_RESET, 0x00);
@@ -2475,31 +2477,49 @@ static void it6505_irq_link_train_fail(struct it6505 *it6505)
 	schedule_work(&it6505->link_works);
 }
 
-static void it6505_irq_video_fifo_error(struct it6505 *it6505)
+static bool it6505_test_bit(unsigned int bit, const unsigned int *addr)
 {
-	struct device *dev = &it6505->client->dev;
+	return 1 & (addr[bit / BITS_PER_BYTE] >> (bit % BITS_PER_BYTE));
+}
 
-	DRM_DEV_DEBUG_DRIVER(dev, "video fifo overflow interrupt");
-	it6505->auto_train_retry = AUTO_TRAIN_RETRY;
-	flush_work(&it6505->link_works);
-	it6505_stop_hdcp(it6505);
-	it6505_video_reset(it6505);
+static bool it6505_is_video_error_int(const int *int_status)
+{
+	if ((it6505_test_bit(BIT_INT_VID_FIFO_ERROR, (unsigned int *)int_status)) || (it6505_test_bit(BIT_INT_IO_FIFO_OVERFLOW, (unsigned int *)int_status)))
+		return 1;
+	return 0;
 }
 
-static void it6505_irq_io_latch_fifo_overflow(struct it6505 *it6505)
+static void it6505_irq_video_error_handler(struct it6505 *it6505)
 {
 	struct device *dev = &it6505->client->dev;
+	int int_status[3] = {0};
+	int reg_0d;
+	int i;
 
-	DRM_DEV_DEBUG_DRIVER(dev, "IO latch fifo overflow interrupt");
 	it6505->auto_train_retry = AUTO_TRAIN_RETRY;
 	flush_work(&it6505->link_works);
 	it6505_stop_hdcp(it6505);
 	it6505_video_reset(it6505);
-}
 
-static bool it6505_test_bit(unsigned int bit, const unsigned int *addr)
-{
-	return 1 & (addr[bit / BITS_PER_BYTE] >> (bit % BITS_PER_BYTE));
+	DRM_DEV_DEBUG_DRIVER(dev, "Video Error reset wait video...");
+
+	for (i = 0; i < 10; i++) {
+		usleep_range(10000, 11000);
+		int_status[2] = it6505_read(it6505, INT_STATUS_03);
+		reg_0d = it6505_read(it6505, REG_SYSTEM_STS);
+		it6505_write(it6505, INT_STATUS_03, int_status[2]);
+
+		DRM_DEV_DEBUG_DRIVER(dev, "reg08 = 0x%02x", int_status[2]);
+		DRM_DEV_DEBUG_DRIVER(dev, "reg0D = 0x%02x", reg_0d);
+
+		if ((reg_0d & VIDEO_STB) && (reg_0d >= 0))
+			break;
+
+		if (it6505_is_video_error_int(int_status)) {
+			it6505_video_reset(it6505);
+			DRM_DEV_DEBUG_DRIVER(dev, "Video Error reset wait video (%d)", i);
+		}
+	}
 }
 
 static irqreturn_t it6505_int_threaded_handler(int unused, void *data)
@@ -2519,8 +2539,6 @@ static irqreturn_t it6505_int_threaded_handler(int unused, void *data)
 		{ BIT_INT_HDCP_KSV_CHECK, it6505_irq_hdcp_ksv_check },
 		{ BIT_INT_AUDIO_FIFO_ERROR, it6505_irq_audio_fifo_error },
 		{ BIT_INT_LINK_TRAIN_FAIL, it6505_irq_link_train_fail },
-		{ BIT_INT_VID_FIFO_ERROR, it6505_irq_video_fifo_error },
-		{ BIT_INT_IO_FIFO_OVERFLOW, it6505_irq_io_latch_fifo_overflow },
 	};
 	int int_status[3], i;
 
@@ -2550,6 +2568,8 @@ static irqreturn_t it6505_int_threaded_handler(int unused, void *data)
 			if (it6505_test_bit(irq_vec[i].bit, (unsigned int *)int_status))
 				irq_vec[i].handler(it6505);
 		}
+		if (it6505_is_video_error_int(int_status))
+			it6505_irq_video_error_handler(it6505);
 	}
 
 	pm_runtime_put_sync(dev);
-- 
2.25.1