From ea4d08578d2e002ce01a2f6913c78fbff8195985 Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime@cerno.tech>
Date: Tue, 29 Jun 2021 11:41:57 +0200
Subject: [PATCH] drm/vc4: hdmi: Make sure the device is powered with
 CEC

Similarly to what we encountered with the detect hook with DRM, nothing
actually prevents any of the CEC callback from being run while the HDMI
output is disabled.

However, this is an issue since any register access to the controller
when it's powered down will result in a silent hang.

Let's make sure we run the runtime_pm hooks when the CEC adapter is
opened and closed by the userspace to avoid that issue.

Fixes: 15b4511a4af6 ("drm/vc4: add HDMI CEC support")
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 7 +++++++
 1 file changed, 7 insertions(+)

--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -1761,6 +1761,11 @@ static int vc4_hdmi_cec_enable(struct ce
 	/* clock period in microseconds */
 	const u32 usecs = 1000000 / CEC_CLOCK_FREQ;
 	u32 val = HDMI_READ(HDMI_CEC_CNTRL_5);
+	int ret;
+
+	ret = pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev);
+	if (ret)
+		return ret;
 
 	val &= ~(VC4_HDMI_CEC_TX_SW_RESET | VC4_HDMI_CEC_RX_SW_RESET |
 		 VC4_HDMI_CEC_CNT_TO_4700_US_MASK |
@@ -1804,6 +1809,8 @@ static int vc4_hdmi_cec_disable(struct c
 	HDMI_WRITE(HDMI_CEC_CNTRL_5, HDMI_READ(HDMI_CEC_CNTRL_5) |
 		   VC4_HDMI_CEC_TX_SW_RESET | VC4_HDMI_CEC_RX_SW_RESET);
 
+	pm_runtime_put(&vc4_hdmi->pdev->dev);
+
 	return 0;
 }
 
