From e9b5643f2ccddbec6c57ec78bf75fd2415d5da0d Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime@cerno.tech>
Date: Wed, 7 Jul 2021 11:51:11 +0200
Subject: drm/vc4: hdmi: Drop devm interrupt handler for hotplug interrupts
Git-commit: 776efe800feda95a29cefecce1ce36cc27d70b29
Patch-mainline: v5.15-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

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>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210707095112.1469670-3-maxime@cerno.tech
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 41 +++++++++++++++++++++++-----------
 1 file changed, 28 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 2144a2dff72b..a5280c97f3c1 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -1584,25 +1584,27 @@ static int vc4_hdmi_hotplug_init(struct vc4_hdmi *vc4_hdmi)
 {
 	struct drm_connector *connector = &vc4_hdmi->connector;
 	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);
+		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;
 	}
@@ -1610,6 +1612,16 @@ static int vc4_hdmi_hotplug_init(struct vc4_hdmi *vc4_hdmi)
 	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)
 {
@@ -2214,7 +2226,7 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
 
 	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)
@@ -2228,6 +2240,8 @@ static int vc4_hdmi_bind(struct device *dev, struct device *master, void *data)
 
 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:
@@ -2269,6 +2283,7 @@ static void vc4_hdmi_unbind(struct device *dev, struct device *master,
 	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);
 
-- 
2.38.1