[PATCH v8 17/19] drm/mediatek: add hpd debounce

[Guillaume Ranquet <granquet@baylibre.com>]

From: Jitao Shi <jitao.shi@mediatek.com>

Implement the DP HDP debounce described in DP 1.4a 3.3.

Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
---
 drivers/gpu/drm/mediatek/mtk_dp.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index 2a3d5f15b651b..fe91ab8b2fd89 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -178,6 +178,8 @@ struct mtk_dp {
 	struct device *codec_dev;
 	u8 connector_eld[MAX_ELD_BYTES];
 	struct drm_connector *conn;
+	bool need_debounce;
+	struct timer_list debounce_timer;
 };
 
 static struct regmap_config mtk_dp_regmap_config = {
@@ -1698,6 +1700,9 @@ static irqreturn_t mtk_dp_hpd_event_thread(int hpd, void *dev)
 	if (event < 0)
 		return IRQ_HANDLED;
 
+	if (mtk_dp->need_debounce && mtk_dp->train_info.cable_plugged_in)
+		msleep(100);
+
 	if (mtk_dp->drm_dev) {
 		dev_info(mtk_dp->dev, "drm_helper_hpd_irq_event\n");
 		drm_helper_hpd_irq_event(mtk_dp->bridge.dev);
@@ -1776,6 +1781,13 @@ static irqreturn_t mtk_dp_hpd_isr_handler(struct mtk_dp *mtk_dp)
 	}
 	train_info->cable_state_change = true;
 
+	if (train_info->cable_state_change) {
+		if (!train_info->cable_plugged_in) {
+			mod_timer(&mtk_dp->debounce_timer, jiffies + msecs_to_jiffies(100) - 1);
+			mtk_dp->need_debounce = false;
+		}
+	}
+
 	return IRQ_WAKE_THREAD;
 }
 
@@ -2239,6 +2251,13 @@ static const struct drm_bridge_funcs mtk_dp_bridge_funcs = {
 	.detect = mtk_dp_bdg_detect,
 };
 
+static void mtk_dp_debounce_timer(struct timer_list *t)
+{
+	struct mtk_dp *mtk_dp = from_timer(mtk_dp, t, debounce_timer);
+
+	mtk_dp->need_debounce = true;
+}
+
 static int mtk_dp_probe(struct platform_device *pdev)
 {
 	struct mtk_dp *mtk_dp;
@@ -2319,6 +2338,9 @@ static int mtk_dp_probe(struct platform_device *pdev)
 	else
 		mtk_dp->bridge.type = DRM_MODE_CONNECTOR_DisplayPort;
 
+	mtk_dp->need_debounce = true;
+	timer_setup(&mtk_dp->debounce_timer, mtk_dp_debounce_timer, 0);
+
 	pm_runtime_enable(dev);
 	pm_runtime_get_sync(dev);
 
@@ -2332,6 +2354,7 @@ static int mtk_dp_remove(struct platform_device *pdev)
 	platform_device_unregister(mtk_dp->phy_dev);
 
 	mtk_dp_video_mute(mtk_dp, true);
+	del_timer_sync(&mtk_dp->debounce_timer);
 
 	pm_runtime_disable(&pdev->dev);
 
-- 
2.34.1