Re: Volume Peak display

[Raymond <rayau@netvigator.com>]

Takashi Iwai wrote:
> At Tue, 21 Jun 2005 17:08:41 +0800,
> Raymond wrote:
> 
 >>static snd_kcontrol_new_t vortex_levels_kcontrol __devinitdata = {
 >>	.iface = SNDRV_CTL_ELEM_IFACE_MIXER,
 >>	.name = "EQ Peaks",
 >>	.access = SNDRV_CTL_ELEM_ACCESS_READ | SNDRV_CTL_ELEM_ACCESS_VOLATILE,
 >>	.info = snd_vortex_peaks_info,
 >>	.get = snd_vortex_peaks_get,
 >>};
 >>
 >>Refer to Alien's png
 >>
 >>http://article.gmane.org/gmane.linux.alsa.devel/23112
 >>
 >>There are 4 sliders marked as "EQ peaks" in alsamixer (1.0.9a) , the
 >>first two are stereo and the last two are mono.
 >>
 >>The 4 EQ peaks sliders in alsamixer can be adjusted and it is strange
 >>that alsamixer do not get "segfault" when ".put" has not been
 >>implemented in au88x0.
 >
 >
 > It shouldn't segfault but be simply ignored.
 >


# amixer cget numid=12 numid=12,iface=MIXER,name='EQ Peaks'
   ; type=INTEGER,access=r----,values=20,min=0,max=32767,step=0
   : values=1,1,0,1,0,0,0,1,0,0,1,1,0,0,0,1,0,1,0,0

# amixer cset numid=12 1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19
amixer: Control default element write error: Operation not permitted

> 
>>The following error only appear with compile with option --with-debug=full
>>
>>Vortex: init.... <3>ALSA control.c:325: control 3:0:0:Playback PCM
>>advanced processing:0 is already present
>>done.
>>
>>It seem that this HRTF kcontrols with 6 values cannot be created.
>>
>>Does it mean that kcontrols ( not enumerated ) cannot contains more than
>>2 values ?
> 
> 
> They can.  The above split of channels is just a matter of mixer
> abstraction layer and alsamixer.  In the control API level, everyhing
> is fine.
> 

The first HRTF kcontrol fail in snd_ctl_add() (there are 16 HRTF 
controls and each contain 6 values).

Is the error cause by numid or duplicate name ?


int snd_ctl_add(snd_card_t * card, snd_kcontrol_t * kcontrol)
{
	snd_ctl_elem_id_t id;
	unsigned int idx;

	snd_runtime_check(card != NULL && kcontrol != NULL, return -EINVAL);
	snd_assert(kcontrol->info != NULL, return -EINVAL);
	id = kcontrol->id;
	down_write(&card->controls_rwsem);
	if (snd_ctl_find_id(card, &id)) {
		up_write(&card->controls_rwsem);
		snd_ctl_free_one(kcontrol);
		snd_printd(KERN_ERR "control %i:%i:%i:%s:%i is already present\n",
					id.iface,
					id.device,
					id.subdevice,
					id.name,
					id.index);
		return -EBUSY;
	}









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