FAILED: patch "[PATCH] drm/vc4: hdmi: Make sure the device is powered with CEC" failed to apply to 5.4-stable tree

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 20b0dfa86bef0e80b41b0e5ac38b92f23b6f27f9 Mon Sep 17 00:00:00 2001
From: Maxime Ripard <[email protected]>
Date: Thu, 19 Aug 2021 15:59:30 +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.

index 1f13e0f00089..8cc84395f4cb 100644
@@ -1741,8 +1741,14 @@ static int vc4_hdmi_cec_enable(struct cec_adapter *adap)
 	struct vc4_hdmi *vc4_hdmi = cec_get_drvdata(adap);
 	/* clock period in microseconds */
 	const u32 usecs = 1000000 / CEC_CLOCK_FREQ;
-	u32 val = HDMI_READ(HDMI_CEC_CNTRL_5);
+	u32 val;
+	int ret;
+
+	ret = pm_runtime_resume_and_get(&vc4_hdmi->pdev->dev);
+	if (ret)
+		return ret;
 
+	val = HDMI_READ(HDMI_CEC_CNTRL_5);
 	val &= ~(VC4_HDMI_CEC_TX_SW_RESET | VC4_HDMI_CEC_RX_SW_RESET |
 		 VC4_HDMI_CEC_CNT_TO_4700_US_MASK |
 		 VC4_HDMI_CEC_CNT_TO_4500_US_MASK);

@@ -1785,6 +1791,8 @@ static int vc4_hdmi_cec_disable(struct cec_adapter *adap)
 	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;
 }