[RFC] New method for adding AC97 SNDRV_CTL_ELEM_TYPE_ENUMERATED controls

[Liam Girdwood <Liam.Girdwood@wolfsonmicro.com>]

I'm interested to know what people think of the following change to the
way that custom controls of type SNDRV_CTL_ELEM_TYPE_ENUMERATED are
added in ac97_codec.c and ac97_patch.c. 

Currently, we have to do something like this for every custom
SNDRV_CTL_ELEM_TYPE_ENUMERATED control we want to add:-

int snd_add_ctl(snd_kcontrol_t *kcontrol, snd_ctl_elem_info_t * uinfo)
{
	static char *texts[6] = {
		"Mic1", "Mic2", "Mono", "Stereo", "Line L", Line R"
	};

	uinfo->type = SNDRV_CTL_ELEM_TYPE_ENUMERATED;
	uinfo->count = 1;
	uinfo->value.enumerated.items = 6;
	if (uinfo->value.enumerated.item > 5)
		uinfo->value.enumerated.item = 5;
	strcpy(uinfo->value.enumerated.name,
texts[uinfo->value.enumerated.item]);
	return 0;
}

I would like to make it easier to add a lot of larger and more complex
controls without the need of adding a lot of new code (and re inveting
the wheel). I'm proposing adding an AC97_ENUM_SINGLE macro i.e.

#define AC97_ENUM_SINGLE(xname, reg, shift, item, invert) \
{ .iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = xname, .info =
snd_ac97_info_enum_single, \
  .get = snd_ac97_get_enum_single, .put = snd_ac97_put_enum_single, \
  .private_value = reg | (shift << 8) | (item << 16) | (invert << 24) }

and also changing AC97_ENUM_DOUBLE:-

#define AC97_ENUM_DOUBLE(xname, reg, shift_l, shift_r, item, invert) \
{ .iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = xname, .info =
snd_ac97_info_enum_double, \
  .get = snd_ac97_get_enum_double, .put = snd_ac97_put_enum_double, \
  .private_value = reg | (shift_l << 8) | (shift_r << 12) | (item << 16)
| (invert << 24) }


This now makes it possible to add the new controls to a regular array of
type snd_kcontrol_new_t. i.e.

static const snd_kcontrol_new_t wm13_snd_ac97_controls_recsel[7] = {
AC97_ENUM_SINGLE("Record to Headphone Path", AC97_VIDEO, 14, 5, 0),
AC97_SINGLE("Record to Headphone Volume", AC97_VIDEO, 11, 7, 0),
AC97_ENUM_SINGLE("Record to Mono Path", AC97_VIDEO, 9, 5, 0),
AC97_SINGLE("Record to Mono Boost (+20dB)", AC97_VIDEO, 8, 1, 0),
AC97_SINGLE("Record ADC Boost (+20dB)", AC97_VIDEO, 6, 1, 0),
AC97_ENUM_SINGLE("Record Select Left", AC97_VIDEO, 3, 6, 0),
AC97_ENUM_SINGLE("Record Select Right", AC97_VIDEO, 0, 7, 0),
};

The text and mask for the control exists in a table of type 

struct ac97_enum_info {
	int mask;	/* number of bits in selector */
	char* text[8];	/* selector description */
};

e.g.

static struct ac97_enum_info enum_info[] = {
	{ 2, {"pre 3D", "post 3D", NULL, NULL, NULL, NULL, NULL, NULL}}, /* std
GP */
	{ 2, {"Mix", "Mic", NULL, NULL, NULL, NULL, NULL, NULL}}, /* std GP */
	{ 2, {"Mic1", "Mic2", NULL, NULL, NULL, NULL, NULL, NULL}}, /* std PG
*/
	{ 8, {"Mic", "CD", "Video", "Aux", "Line", "Mix", "Mix Mono",
"Phone"}}, /* std REC select */
	{ 4, {"Stereo", "Mic1", "Mic2", "Mute", NULL, NULL, NULL, NULL}},
	{ 4, {"Stereo", "Left", "Right", "Mute", NULL, NULL, NULL, NULL}},
	{ 8, {"Mic1", "Mic2", "Line L", "Mono In", "HP Mix L", "Spk Mix", "Mono
Mix", "Zh"}},
	{ 8, {"Mic1", "Mic2", "Line R", "Mono In", "HP Mix R", "Spk Mix", "Mono
Mix", "Zh"}},
};


I've already implemented this for the wm9713 codec and it works well. I
can now add new routing and mixer enum controls very quickly without too
much new driver bloat.

If this is acceptable, I'll submit a patch.

Liam 





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