ALSA: hda: Disable 4/6 channels on some NVIDIA GPUs.

Added hardware constraint in patch_hdmi.c to disable
channels 4/6 which are not supported by some older
NVIDIA GPUs.
Signed-off-by: Nitin Daga <ndaga@nvidia.com>
Acked-By: Stephen Warren <swarren@nvidia.com>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/patch_hdmi.c

@@ -1193,11 +1193,53 @@ static int nvhdmi_7x_init(struct hda_codec *codec)
 	return 0;
 }
 
+static unsigned int channels_2_6_8[] = {
+	2, 6, 8
+};
+
+static unsigned int channels_2_8[] = {
+	2, 8
+};
+
+static struct snd_pcm_hw_constraint_list hw_constraints_2_6_8_channels = {
+	.count = ARRAY_SIZE(channels_2_6_8),
+	.list = channels_2_6_8,
+	.mask = 0,
+};
+
+static struct snd_pcm_hw_constraint_list hw_constraints_2_8_channels = {
+	.count = ARRAY_SIZE(channels_2_8),
+	.list = channels_2_8,
+	.mask = 0,
+};
+
 static int simple_playback_pcm_open(struct hda_pcm_stream *hinfo,
 				    struct hda_codec *codec,
 				    struct snd_pcm_substream *substream)
 {
 	struct hdmi_spec *spec = codec->spec;
+	struct snd_pcm_hw_constraint_list *hw_constraints_channels = NULL;
+
+	switch (codec->preset->id) {
+	case 0x10de0002:
+	case 0x10de0003:
+	case 0x10de0005:
+	case 0x10de0006:
+		hw_constraints_channels = &hw_constraints_2_8_channels;
+		break;
+	case 0x10de0007:
+		hw_constraints_channels = &hw_constraints_2_6_8_channels;
+		break;
+	default:
+		break;
+	}
+
+	if (hw_constraints_channels != NULL) {
+		snd_pcm_hw_constraint_list(substream->runtime, 0,
+				SNDRV_PCM_HW_PARAM_CHANNELS,
+				hw_constraints_channels);
+	}
+
 	return snd_hda_multi_out_dig_open(codec, &spec->multiout);
 }