From fda46a52e84a5160d7277e55e1c1be376b0ba579 Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime@cerno.tech>
Date: Mon, 5 Jul 2021 17:31:48 +0200
Subject: [PATCH] drm/vc4: hdmi: Drop devm interrupt handler for
 hotplug interrupts

The hotplugs interrupt handlers are registered through the
devm_request_threaded_irq function. However, while free_irq is indeed
called properly when the device is unbound or bind fails, it's called
after unbind or bind is done.

In our particular case, it means that on failure it creates a window
where our interrupt handler can be called, but we're freeing every
resource (CEC adapter, DRM objects, etc.) it might need.

In order to address this, let's switch to the non-devm variant to
control better when the handler will be unregistered and allow us to
make it safe.

Fixes: f4790083c7c2 ("drm/vc4: hdmi: Rely on interrupts to handle hotplug")
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 41 +++++++++++++++++++++++-----------
 1 file changed, 28 insertions(+), 13 deletions(-)

--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -1613,26 +1613,28 @@ static irqreturn_t vc4_hdmi_hpd_irq_thre
 static int vc4_hdmi_hotplug_init(struct vc4_hdmi *vc4_hdmi)
 {
 	struct platform_device *pdev = vc4_hdmi->pdev;
-	struct device *dev = &pdev->dev;
 	struct drm_connector *connector = &vc4_hdmi->connector;
 	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);
+		unsigned int hpd_con = platform_get_irq_byname(pdev, "hpd-connected");
+		unsigned int hpd_rm = platform_get_irq_byname(pdev, "hpd-removed");
+
+		ret = request_threaded_irq(hpd_con,
+					   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)
+		ret = request_threaded_irq(hpd_rm,
+					   NULL,
+					   vc4_hdmi_hpd_irq_thread, IRQF_ONESHOT,
+					   "vc4 hdmi hpd disconnected", vc4_hdmi);
+		if (ret) {
+			free_irq(hpd_con, vc4_hdmi);
 			return ret;
+		}
 
 		connector->polled = DRM_CONNECTOR_POLL_HPD;
 	}
@@ -1640,6 +1642,16 @@ static int vc4_hdmi_hotplug_init(struct
 	return 0;
 }
 
+static void vc4_hdmi_hotplug_exit(struct vc4_hdmi *vc4_hdmi)
+{
+	struct platform_device *pdev = vc4_hdmi->pdev;
+
+	if (vc4_hdmi->variant->external_irq_controller) {
+		free_irq(platform_get_irq_byname(pdev, "hpd-connected"), vc4_hdmi);
+		free_irq(platform_get_irq_byname(pdev, "hpd-removed"), vc4_hdmi);
+	}
+}
+
 #ifdef CONFIG_DRM_VC4_HDMI_CEC
 static irqreturn_t vc4_cec_irq_handler_rx_thread(int irq, void *priv)
 {
@@ -2307,7 +2319,7 @@ static int vc4_hdmi_bind(struct device *
 
 	ret = vc4_hdmi_cec_init(vc4_hdmi);
 	if (ret)
-		goto err_destroy_conn;
+		goto err_free_hotplug;
 
 	ret = vc4_hdmi_audio_init(vc4_hdmi);
 	if (ret)
@@ -2321,6 +2333,8 @@ static int vc4_hdmi_bind(struct device *
 
 err_free_cec:
 	vc4_hdmi_cec_exit(vc4_hdmi);
+err_free_hotplug:
+	vc4_hdmi_hotplug_exit(vc4_hdmi);
 err_destroy_conn:
 	vc4_hdmi_connector_destroy(&vc4_hdmi->connector);
 err_destroy_encoder:
@@ -2362,6 +2376,7 @@ static void vc4_hdmi_unbind(struct devic
 	kfree(vc4_hdmi->hd_regset.regs);
 
 	vc4_hdmi_cec_exit(vc4_hdmi);
+	vc4_hdmi_hotplug_exit(vc4_hdmi);
 	vc4_hdmi_connector_destroy(&vc4_hdmi->connector);
 	drm_encoder_cleanup(&vc4_hdmi->encoder.base.base);
 
