From: Bo-Chen Chen <rex-bc.chen@mediatek.com>
To: <chunkuang.hu@kernel.org>, <p.zabel@pengutronix.de>,
<daniel@ffwll.ch>, <robh+dt@kernel.org>,
<krzysztof.kozlowski+dt@linaro.org>, <mripard@kernel.org>,
<tzimmermann@suse.de>, <matthias.bgg@gmail.com>, <deller@gmx.de>,
<airlied@linux.ie>
Cc: <msp@baylibre.com>, <granquet@baylibre.com>,
<jitao.shi@mediatek.com>, <wenst@chromium.org>,
<angelogioacchino.delregno@collabora.com>, <ck.hu@mediatek.com>,
<liangxu.xu@mediatek.com>, <dri-devel@lists.freedesktop.org>,
<linux-mediatek@lists.infradead.org>,
<devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
<linux-arm-kernel@lists.infradead.org>,
<linux-fbdev@vger.kernel.org>,
<Project_Global_Chrome_Upstream_Group@mediatek.com>,
Bo-Chen Chen <rex-bc.chen@mediatek.com>
Subject: [PATCH v16 5/8] drm/mediatek: add hpd debounce
Date: Fri, 5 Aug 2022 18:14:56 +0800 [thread overview]
Message-ID: <20220805101459.3386-6-rex-bc.chen@mediatek.com> (raw)
In-Reply-To: <20220805101459.3386-1-rex-bc.chen@mediatek.com>
From: Jitao Shi <jitao.shi@mediatek.com>
From the DP spec 1.4a chapter 3.3, upstream devices should implement
HPD signal de-bouncing on an external connection.
A period of 100ms should be used to detect an HPD connect event.
To cover these cases, HPD de-bounce should be implemented only after
HPD low has been detected for at least 100ms.
Therefore,
1. If HPD is low (which means plugging out) for longer than 100ms:
we need to do de-bouncing (which means we need to wait for 100ms).
2. If HPD low is for less than 100ms:
we don't need to care about the de-bouncing.
In this patch, we start a 100ms timer and use a need_debounce boolean
to implement the feature.
Two cases when HPD is high:
1. If the timer is expired (>100ms):
- need_debounce is true.
- When HPD high (plugging event comes), need_debounce will be true
and then we need to do de-bouncing (wait for 100ms).
2. If the timer is not expired (<100ms):
- need_debounce is false.
- When HPD high (plugging event comes), need_debounce will be false
and no need to do de-bouncing.
HPD_______ __________________
| |<- 100ms ->
|____________|
<- 100ms ->
Without HPD de-bouncing, USB-C to HDMI Adapaters will not be detected.
The change has been successfully tested with the following devices:
- Dell Adapter - USB-C to HDMI
- Acer 1in1 HDMI dongle
- Ugreen 1in1 HDMI dongle
- innowatt HDMI + USB3 hub
- Acer 2in1 HDMI dongle
- Apple 3in1 HDMI dongle (A2119)
- J5Create 3in1 HDMI dongle (JAC379)
Tested-by: Rex-BC Chen <rex-bc.chen@mediatek.com>
Reviewed-by: Rex-BC Chen <rex-bc.chen@mediatek.com>
Signed-off-by: Jitao Shi <jitao.shi@mediatek.com>
Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
---
drivers/gpu/drm/mediatek/mtk_dp.c | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index 00971ea2fadf..487f3ed0c19f 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -95,6 +95,8 @@ struct mtk_dp {
bool enabled;
struct drm_connector *conn;
+ bool need_debounce;
+ struct timer_list debounce_timer;
};
struct mtk_dp_data {
@@ -1479,6 +1481,9 @@ static irqreturn_t mtk_dp_hpd_event_thread(int hpd, void *dev)
dev_dbg(mtk_dp->dev, "MTK_DP_HPD_INTERRUPT\n");
+ if (mtk_dp->need_debounce && mtk_dp->train_info.cable_plugged_in)
+ msleep(100);
+
drm_helper_hpd_irq_event(mtk_dp->bridge.dev);
mtk_dp->train_info.hpd_inerrupt = false;
mtk_dp_hpd_sink_event(mtk_dp);
@@ -1525,6 +1530,10 @@ static irqreturn_t mtk_dp_hpd_event(int hpd, void *dev)
mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
DP_PWR_STATE_BANDGAP_TPLL,
DP_PWR_STATE_MASK);
+
+ mod_timer(&mtk_dp->debounce_timer,
+ jiffies + msecs_to_jiffies(100) - 1);
+ mtk_dp->need_debounce = false;
} else {
mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_PWR_STATE,
DP_PWR_STATE_BANDGAP_TPLL_LANE,
@@ -1945,6 +1954,13 @@ 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;
@@ -2020,6 +2036,9 @@ static int mtk_dp_probe(struct platform_device *pdev)
drm_bridge_add(&mtk_dp->bridge);
+ 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);
@@ -2032,6 +2051,7 @@ 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);
--
2.18.0
next prev parent reply other threads:[~2022-08-05 10:15 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-05 10:14 [PATCH v16 0/8] drm/mediatek: Add MT8195 DisplayPort driver Bo-Chen Chen
2022-08-05 10:14 ` [PATCH v16 1/8] dt-bindings: mediatek,dp: Add Display Port binding Bo-Chen Chen
2022-08-09 19:46 ` Rob Herring
2022-08-05 10:14 ` [PATCH v16 2/8] video/hdmi: Add audio_infoframe packing for DP Bo-Chen Chen
2022-08-05 10:14 ` [PATCH v16 3/8] drm/mediatek: Add MT8195 Embedded DisplayPort driver Bo-Chen Chen
2022-08-08 4:03 ` CK Hu
2022-08-08 4:48 ` CK Hu
2022-08-08 5:16 ` CK Hu
2022-08-08 5:21 ` CK Hu
2022-08-09 8:06 ` Bo-Chen Chen
2022-08-08 5:46 ` CK Hu
2022-08-09 7:57 ` Bo-Chen Chen
2022-08-08 5:50 ` CK Hu
2022-08-08 8:04 ` CK Hu
2022-08-09 8:01 ` Bo-Chen Chen
2022-08-05 10:14 ` [PATCH v16 4/8] drm/mediatek: Add MT8195 External DisplayPort support Bo-Chen Chen
2022-08-08 3:56 ` CK Hu
2022-08-05 10:14 ` Bo-Chen Chen [this message]
2022-08-05 10:14 ` [PATCH v16 6/8] drm/mediatek: set monitor to DP_SET_POWER_D3 to avoid garbage Bo-Chen Chen
2022-08-05 10:14 ` [PATCH v16 7/8] drm/mediatek: DP audio support for MT8195 Bo-Chen Chen
2022-08-05 10:14 ` [PATCH v16 8/8] drm/mediatek: Use cached audio config when changing resolution Bo-Chen Chen
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