ALSA: hda - Don't give over 0dB volume for AD1984A HP laptops

Set the upper limit 0dB to the volume of mixer amp 0x20 for
AD1984A HP laptops.  The overloaded volume may damage the internal
speaker.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/patch_analog.c

@@ -3986,6 +3986,14 @@ static int patch_ad1884a(struct hda_codec *codec)
 		spec->multiout.dig_out_nid = 0;
 		codec->patch_ops.unsol_event = ad1884a_hp_unsol_event;
 		codec->patch_ops.init = ad1884a_hp_init;
+		/* set the upper-limit for mixer amp to 0dB for avoiding the
+		 * possible damage by overloading
+		 */
+		snd_hda_override_amp_caps(codec, 0x20, HDA_INPUT,
+					  (0x17 << AC_AMPCAP_OFFSET_SHIFT) |
+					  (0x17 << AC_AMPCAP_NUM_STEPS_SHIFT) |
+					  (0x05 << AC_AMPCAP_STEP_SIZE_SHIFT) |
+					  (1 << AC_AMPCAP_MUTE_SHIFT));
 		break;
 	case AD1884A_THINKPAD:
 		spec->mixers[0] = ad1984a_thinkpad_mixers;