[alsa-devel] PCM Volume on FSC V5505

[Takashi Iwai]

At Fri, 23 Nov 2007 17:45:21 +0100,
Jan-Simon Möller wrote:
> 
> Hi !
> With the patches, the sound works - well done! 
> But I need to make sure the PCM volume is max @ 50% .
> If its over 50% sound is clipped and ugly (overload?).

Looks like so.  Mixer apps (e.g. alsamixer) can show its dB value
instead of percent.  Check the dB level shown there.

The patch below may fix this issue.  Give it a try.


Takashi

diff -r 17223a4918b4 pci/hda/patch_conexant.c
--- a/pci/hda/patch_conexant.c	Tue Nov 27 15:27:17 2007 +0100
+++ b/pci/hda/patch_conexant.c	Tue Nov 27 16:46:15 2007 +0100
@@ -826,6 +826,17 @@ static int patch_cxt5045(struct hda_code
 		spec->init_verbs[0] = cxt5045_test_init_verbs;
 #endif	
 	}
+
+	/*
+	 * Fix max PCM level to 0 dB
+	 * (originall it has 0x2b steps with 0dB offset 0x14)
+	 */
+	snd_hda_override_amp_caps(codec, 0x17, HDA_OUTPUT,
+				  (0x14 << AC_AMPCAP_OFFSET_SHIFT) |
+				  (0x14 << AC_AMPCAP_NUM_STEPS_SHIFT) |
+				  (0x05 << AC_AMPCAP_STEP_SIZE_SHIFT) |
+				  (1 << AC_AMPCAP_MUTE_SHIFT));
+
 	return 0;
 }