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

[Guillaume Ranquet]

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

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

Signed-off-by: Jitao Shi <jitao....@mediatek.com>
Signed-off-by: Guillaume Ranquet <granq...@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