linux-kernel - [PATCH 5.15 091/846] drm/vc4: hdmi: Make sure the controller is powered in detect

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Date:   Mon, 24 Jan 2022 19:33:28 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Maxime Ripard <maxime@...no.tech>,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        Nicolas Saenz Julienne <nsaenz@...nel.org>,
        Michael Stapelberg <michael@...pelberg.ch>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.15 091/846] drm/vc4: hdmi: Make sure the controller is powered in detect

From: Maxime Ripard <maxime@...no.tech>

[ Upstream commit 0f5251339eda7f7eb7bd4467607ae1d01b24e129 ]

If the HPD GPIO is not available and drm_probe_ddc fails, we end up
reading the HDMI_HOTPLUG register, but the controller might be powered
off resulting in a CPU hang. Make sure we have the power domain and the
HSM clock powered during the detect cycle to prevent the hang from
happening.

Fixes: 4f6e3d66ac52 ("drm/vc4: Add runtime PM support to the HDMI encoder driver")
Signed-off-by: Maxime Ripard <maxime@...no.tech>
Reviewed-by: Dave Stevenson <dave.stevenson@...pberrypi.com>
Reviewed-by: Nicolas Saenz Julienne <nsaenz@...nel.org>
Tested-by: Nicolas Saenz Julienne <nsaenz@...nel.org>
Tested-by: Michael Stapelberg <michael@...pelberg.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210922125419.4125779-6-maxime@cerno.tech
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 6b0700d0b408e..21510ae31a9ec 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -168,6 +168,8 @@ vc4_hdmi_connector_detect(struct drm_connector *connector, bool force)
 	struct vc4_hdmi *vc4_hdmi = connector_to_vc4_hdmi(connector);
 	bool connected = false;
 
+	WARN_ON(pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev));
+
 	if (vc4_hdmi->hpd_gpio &&
 	    gpiod_get_value_cansleep(vc4_hdmi->hpd_gpio)) {
 		connected = true;
@@ -188,10 +190,12 @@ vc4_hdmi_connector_detect(struct drm_connector *connector, bool force)
 			}
 		}
 
+		pm_runtime_put(&vc4_hdmi->pdev->dev);
 		return connector_status_connected;
 	}
 
 	cec_phys_addr_invalidate(vc4_hdmi->cec_adap);
+	pm_runtime_put(&vc4_hdmi->pdev->dev);
 	return connector_status_disconnected;
 }
 
-- 
2.34.1