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Message-Id: <20220327223927.20848-21-granquet@baylibre.com>
Date: Mon, 28 Mar 2022 00:39:25 +0200
From: Guillaume Ranquet <granquet@...libre.com>
To: airlied@...ux.ie, angelogioacchino.delregno@...labora.com,
chunfeng.yun@...iatek.com, chunkuang.hu@...nel.org,
ck.hu@...iatek.com, daniel@...ll.ch, deller@....de,
jitao.shi@...iatek.com, kishon@...com, krzk+dt@...nel.org,
maarten.lankhorst@...ux.intel.com, matthias.bgg@...il.com,
mripard@...nel.org, p.zabel@...gutronix.de, robh+dt@...nel.org,
tzimmermann@...e.de, vkoul@...nel.org
Cc: devicetree@...r.kernel.org, dri-devel@...ts.freedesktop.org,
linux-arm-kernel@...ts.infradead.org, linux-fbdev@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-mediatek@...ts.infradead.org,
linux-phy@...ts.infradead.org, markyacoub@...gle.com,
Rex-BC Chen <rex-bc.chen@...iatek.com>
Subject: [PATCH v9 20/22] drm/mediatek: add hpd debounce
From: Jitao Shi <jitao.shi@...iatek.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@...iatek.com>
Reviewed-by: Rex-BC Chen <rex-bc.chen@...iatek.com>
Signed-off-by: Jitao Shi <jitao.shi@...iatek.com>
Signed-off-by: Guillaume Ranquet <granquet@...libre.com>
---
drivers/gpu/drm/mediatek/mtk_dp.c | 46 +++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)
diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index 9e532408f12e..e099491cc6a4 100644
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -174,6 +174,33 @@ 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;
+};
+
+enum mtk_dp_sdp_type {
+ MTK_DP_SDP_NONE = 0x00,
+ MTK_DP_SDP_ACM = 0x01,
+ MTK_DP_SDP_ISRC = 0x02,
+ MTK_DP_SDP_AVI = 0x03,
+ MTK_DP_SDP_AUI = 0x04,
+ MTK_DP_SDP_SPD = 0x05,
+ MTK_DP_SDP_MPEG = 0x06,
+ MTK_DP_SDP_NTSC = 0x07,
+ MTK_DP_SDP_VSP = 0x08,
+ MTK_DP_SDP_VSC = 0x09,
+ MTK_DP_SDP_EXT = 0x0A,
+ MTK_DP_SDP_PPS0 = 0x0B,
+ MTK_DP_SDP_PPS1 = 0x0C,
+ MTK_DP_SDP_PPS2 = 0x0D,
+ MTK_DP_SDP_PPS3 = 0x0E,
+ MTK_DP_SDP_DRM = 0x10,
+ MTK_DP_SDP_MAX_NUM
+};
+
+struct mtk_dp_sdp_packet {
+ enum mtk_dp_sdp_type type;
+ struct dp_sdp sdp;
};
static bool mtk_dp_is_edp(struct mtk_dp *mtk_dp)
@@ -1812,6 +1839,9 @@ 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);
@@ -1890,6 +1920,11 @@ static irqreturn_t mtk_dp_hpd_isr_handler(struct mtk_dp *mtk_dp)
}
train_info->cable_state_change = true;
+ 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;
}
@@ -2337,6 +2372,13 @@ 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;
@@ -2394,6 +2436,9 @@ static int mtk_dp_probe(struct platform_device *pdev)
mtk_dp->bridge.of_node = dev->of_node;
mtk_dp->bridge.type = DRM_MODE_CONNECTOR_eDP;
+ mtk_dp->need_debounce = true;
+ timer_setup(&mtk_dp->debounce_timer, mtk_dp_debounce_timer, 0);
+
mtk_dp->bridge.ops =
DRM_BRIDGE_OP_DETECT | DRM_BRIDGE_OP_EDID | DRM_BRIDGE_OP_HPD;
drm_bridge_add(&mtk_dp->bridge);
@@ -2413,6 +2458,7 @@ static int mtk_dp_remove(struct platform_device *pdev)
struct mtk_dp *mtk_dp = platform_get_drvdata(pdev);
mtk_dp_video_mute(mtk_dp, true);
+ del_timer_sync(&mtk_dp->debounce_timer);
pm_runtime_disable(&pdev->dev);
--
2.34.1
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