ASoC: hdac: make SOF HDA codec driver probe deterministic

To provide backward compatibility to older systems, the SOF HDA driver
allows user to specify which HDMI codec driver to use at runtime via
kernel parameter. This mechanism has a subtle flaw in that it assumes
the codec drivers not to be loaded when the SOF PCI driver is loaded.

The problem is rooted in use of the hdev->type field.
snd_hdac_ext_bus_device_init() initializes this field to HDA_DEV_ASOC.
This signals the HDA core that ASoC drivers should be considered in
driver matching (hda_bus_match()). The SOF and SST drivers continue by
overriding this field to HDA_DEV_LEGACY and proceeding to load driver
modules with request_module(). Correct drivers will get loaded and
attached.

If however the codec drivers are already loaded when
snd_hdac_ext_bus_device_init() is called, the matching will not work as
expected as device type is still set to HDA_DEV_ASOC. Specifically if
hdac-hdmi is attached when machine driver is configured to use hdac-hda,
this leads to out-of-bounds memory access in
hda_dsp_hdmi_build_controls().

Fix the issue by adding codec type as a parameter to
snd_hdac_ext_bus_device_init() and ensuring type is set correctly from
the start.

Fixes: 139c7feb ("ASoC: SOF: Intel: add support for snd-hda-codec-hdmi")
Signed-off-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20200921100841.2882662-1-kai.vehmanen@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

include/sound/hdaudio_ext.h

@@ -10,7 +10,7 @@ int snd_hdac_ext_bus_init(struct hdac_bus *bus, struct device *dev,
 
 void snd_hdac_ext_bus_exit(struct hdac_bus *bus);
 int snd_hdac_ext_bus_device_init(struct hdac_bus *bus, int addr,
-						struct hdac_device *hdev);
+				struct hdac_device *hdev, int type);
 void snd_hdac_ext_bus_device_exit(struct hdac_device *hdev);
 void snd_hdac_ext_bus_device_remove(struct hdac_bus *bus);
 

sound/hda/ext/hdac_ext_bus.c

@@ -70,11 +70,12 @@ static void default_release(struct device *dev)
  * @bus: hdac bus to attach to
  * @addr: codec address
  * @hdev: hdac device to init
+ * @type: codec type (HDAC_DEV_*) to use for this device
  *
  * Returns zero for success or a negative error code.
  */
 int snd_hdac_ext_bus_device_init(struct hdac_bus *bus, int addr,
-					struct hdac_device *hdev)
+				 struct hdac_device *hdev, int type)
 {
 	char name[15];
 	int ret;
@@ -88,7 +89,7 @@ int snd_hdac_ext_bus_device_init(struct hdac_bus *bus, int addr,
 		dev_err(bus->dev, "device init failed for hdac device\n");
 		return ret;
 	}
-	hdev->type = HDA_DEV_ASOC;
+	hdev->type = type;
 	hdev->dev.release = default_release;
 
 	ret = snd_hdac_device_register(hdev);

sound/soc/intel/skylake/skl.c

@@ -721,7 +721,7 @@ static int probe_codec(struct hdac_bus *bus, int addr)
 	hda_codec->codec.bus = skl_to_hbus(skl);
 	hdev = &hda_codec->codec.core;
 
-	err = snd_hdac_ext_bus_device_init(bus, addr, hdev);
+	err = snd_hdac_ext_bus_device_init(bus, addr, hdev, HDA_DEV_ASOC);
 	if (err < 0)
 		return err;
 
@@ -736,7 +736,7 @@ static int probe_codec(struct hdac_bus *bus, int addr)
 	if (!hdev)
 		return -ENOMEM;
 
-	return snd_hdac_ext_bus_device_init(bus, addr, hdev);
+	return snd_hdac_ext_bus_device_init(bus, addr, hdev, HDA_DEV_ASOC);
 #endif /* CONFIG_SND_SOC_INTEL_SKYLAKE_HDAUDIO_CODEC */
 }
 

sound/soc/sof/intel/hda-codec.c

@@ -117,6 +117,7 @@ static int hda_codec_probe(struct snd_sof_dev *sdev, int address,
 #if IS_ENABLED(CONFIG_SND_SOC_SOF_HDA_AUDIO_CODEC)
 	struct hdac_hda_priv *hda_priv;
 	struct hda_codec *codec;
+	int type = HDA_DEV_LEGACY;
 #endif
 	struct hda_bus *hbus = sof_to_hbus(sdev);
 	struct hdac_device *hdev;
@@ -143,7 +144,11 @@ static int hda_codec_probe(struct snd_sof_dev *sdev, int address,
 	hdev = &hda_priv->codec.core;
 	codec = &hda_priv->codec;
 
-	ret = snd_hdac_ext_bus_device_init(&hbus->core, address, hdev);
+	/* only probe ASoC codec drivers for HDAC-HDMI */
+	if (!hda_codec_use_common_hdmi && (resp & 0xFFFF0000) == IDISP_VID_INTEL)
+		type = HDA_DEV_ASOC;
+
+	ret = snd_hdac_ext_bus_device_init(&hbus->core, address, hdev, type);
 	if (ret < 0)
 		return ret;
 
@@ -161,13 +166,7 @@ static int hda_codec_probe(struct snd_sof_dev *sdev, int address,
 	else
 		codec->probe_id = 0;
 
-	/*
-	 * if common HDMI codec driver is not used, codec load
-	 * is skipped here and hdac_hdmi is used instead
-	 */
-	if (hda_codec_use_common_hdmi ||
-	    (resp & 0xFFFF0000) != IDISP_VID_INTEL) {
-		hdev->type = HDA_DEV_LEGACY;
+	if (type == HDA_DEV_LEGACY) {
 		ret = hda_codec_load_module(codec);
 		/*
 		 * handle ret==0 (no driver bound) as an error, but pass
@@ -188,7 +187,7 @@ static int hda_codec_probe(struct snd_sof_dev *sdev, int address,
 	if (!hdev)
 		return -ENOMEM;
 
-	ret = snd_hdac_ext_bus_device_init(&hbus->core, address, hdev);
+	ret = snd_hdac_ext_bus_device_init(&hbus->core, address, hdev, HDA_DEV_ASOC);
 
 	return ret;
 #endif