linux-kernel - [PATCH] drm/vc4: hdmi: Rely on interrupts to handle hotplug

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Date:   Mon, 24 May 2021 15:20:18 +0200
From:   Maxime Ripard <maxime@...no.tech>
To:     dri-devel@...ts.freedesktop.org,
        Daniel Vetter <daniel.vetter@...el.com>,
        David Airlie <airlied@...ux.ie>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        Maxime Ripard <maxime@...no.tech>
Cc:     Eric Anholt <eric@...olt.net>,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        Phil Elwell <phil@...pberrypi.com>,
        Tim Gover <tim.gover@...pberrypi.com>,
        Dom Cobley <dom@...pberrypi.com>, linux-kernel@...r.kernel.org,
        Daniel Vetter <daniel@...ll.ch>,
        Maxime Ripard <mripard@...nel.org>
Subject: [PATCH] drm/vc4: hdmi: Rely on interrupts to handle hotplug

DRM currently polls for the HDMI connector status every 10s, which can
be an issue when we connect/disconnect a display quickly or the device
on the other end only issues a hotplug pulse (for example on EDID
change).

Switch the driver to rely on the internal controller logic for the
BCM2711/RPi4.

Signed-off-by: Maxime Ripard <maxime@...no.tech>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 44 ++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index c27b287d2053..3988969f7410 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -1510,6 +1510,46 @@ static int vc4_hdmi_audio_init(struct vc4_hdmi *vc4_hdmi)
 
 }
 
+static irqreturn_t vc4_hdmi_hpd_irq_thread(int irq, void *priv)
+{
+	struct vc4_hdmi *vc4_hdmi = priv;
+	struct drm_device *dev = vc4_hdmi->connector.dev;
+
+	if (dev)
+		drm_kms_helper_hotplug_event(dev);
+
+	return IRQ_HANDLED;
+}
+
+static int vc4_hdmi_hotplug_init(struct vc4_hdmi *vc4_hdmi)
+{
+	struct platform_device *pdev = vc4_hdmi->pdev;
+	struct device *dev = &pdev->dev;
+	int ret;
+
+	if (vc4_hdmi->variant->external_irq_controller) {
+		ret = devm_request_threaded_irq(dev,
+						platform_get_irq_byname(pdev, "hpd-connected"),
+						NULL,
+						vc4_hdmi_hpd_irq_thread, IRQF_ONESHOT,
+						"vc4 hdmi hpd connected", vc4_hdmi);
+		if (ret)
+			return ret;
+
+		ret = devm_request_threaded_irq(dev,
+						platform_get_irq_byname(pdev, "hpd-removed"),
+						NULL,
+						vc4_hdmi_hpd_irq_thread, IRQF_ONESHOT,
+						"vc4 hdmi hpd disconnected", vc4_hdmi);
+		if (ret)
+			return ret;
+
+		connector->polled = DRM_CONNECTOR_POLL_HPD;
+	}
+
+	return 0;
+}
+
 #ifdef CONFIG_DRM_VC4_HDMI_CEC
 static irqreturn_t vc4_cec_irq_handler_rx_thread(int irq, void *priv)
 {
@@ -2060,6 +2100,10 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
 	if (ret)
 		goto err_destroy_encoder;
 
+	ret = vc4_hdmi_hotplug_init(vc4_hdmi);
+	if (ret)
+		goto err_destroy_conn;
+
 	ret = vc4_hdmi_cec_init(vc4_hdmi);
 	if (ret)
 		goto err_destroy_conn;
-- 
2.31.1