From c43ce5126b1e09ab81b26b9933782e30fc238166 Mon Sep 17 00:00:00 2001
From: Maxime Ripard <maxime@cerno.tech>
Date: Mon, 25 Oct 2021 16:11:11 +0200
Subject: drm/vc4: hdmi: Check the device state in prepare()
Git-commit: a64ff88cb5eb0b9a6855a24ff326e948931e3a8e
Patch-mainline: v5.17-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

Even though we already check that the encoder->crtc pointer is there
during in startup(), which is part of the open() path in ASoC, nothing
guarantees that our encoder state won't change between the time when we
open the device and the time we prepare it.

Move the sanity checks we do in startup() to a helper and call it from
prepare().

Link: https://lore.kernel.org/r/20211025141113.702757-8-maxime@cerno.tech
Fixes: 91e99e113929 ("drm/vc4: hdmi: Register HDMI codec")
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/vc4/vc4_hdmi.c | 35 +++++++++++++++++++++++++++-------
 1 file changed, 28 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c
index 949015869f3a..eb4909995989 100644
--- a/drivers/gpu/drm/vc4/vc4_hdmi.c
+++ b/drivers/gpu/drm/vc4/vc4_hdmi.c
@@ -1395,20 +1395,36 @@ static inline struct vc4_hdmi *dai_to_hdmi(struct snd_soc_dai *dai)
 	return snd_soc_card_get_drvdata(card);
 }
 
+static bool vc4_hdmi_audio_can_stream(struct vc4_hdmi *vc4_hdmi)
+{
+	struct drm_encoder *encoder = &vc4_hdmi->encoder.base.base;
+
+	lockdep_assert_held(&vc4_hdmi->mutex);
+
+	/*
+	 * The encoder doesn't have a CRTC until the first modeset.
+	 */
+	if (!encoder->crtc)
+		return false;
+
+	/*
+	 * If the encoder is currently in DVI mode, treat the codec DAI
+	 * as missing.
+	 */
+	if (!(HDMI_READ(HDMI_RAM_PACKET_CONFIG) & VC4_HDMI_RAM_PACKET_ENABLE))
+		return false;
+
+	return true;
+}
+
 static int vc4_hdmi_audio_startup(struct device *dev, void *data)
 {
 	struct vc4_hdmi *vc4_hdmi = dev_get_drvdata(dev);
-	struct drm_encoder *encoder = &vc4_hdmi->encoder.base.base;
 	unsigned long flags;
 
 	mutex_lock(&vc4_hdmi->mutex);
 
-	/*
-	 * If the HDMI encoder hasn't probed, or the encoder is
-	 * currently in DVI mode, treat the codec dai as missing.
-	 */
-	if (!encoder->crtc || !(HDMI_READ(HDMI_RAM_PACKET_CONFIG) &
-				VC4_HDMI_RAM_PACKET_ENABLE)) {
+	if (!vc4_hdmi_audio_can_stream(vc4_hdmi)) {
 		mutex_unlock(&vc4_hdmi->mutex);
 		return -ENODEV;
 	}
@@ -1538,6 +1554,11 @@ static int vc4_hdmi_audio_prepare(struct device *dev, void *data,
 
 	mutex_lock(&vc4_hdmi->mutex);
 
+	if (!vc4_hdmi_audio_can_stream(vc4_hdmi)) {
+		mutex_unlock(&vc4_hdmi->mutex);
+		return -EINVAL;
+	}
+
 	vc4_hdmi_audio_set_mai_clock(vc4_hdmi, sample_rate);
 
 	spin_lock_irqsave(&vc4_hdmi->hw_lock, flags);
-- 
2.38.1