Merge tag 'mute-led-rework' of https://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound into asoc-5.13

ALSA: control - add generic LED API

This patchset tries to resolve the diversity in the audio LED
control among the ALSA drivers. A new control layer registration
is introduced which allows to run additional operations on
top of the elementary ALSA sound controls.

A new control access group (three bits in the access flags)
was introduced to carry the LED group information for
the sound controls. The low-level sound drivers can just
mark those controls using this access group. This information
is not exported to the user space, but user space can
manage the LED sound control associations through sysfs
(last patch) per Mark's request. It makes things fully
configurable in the kernel and user space (UCM).

The actual state ('route') evaluation is really easy
(the minimal value check for all channels / controls / cards).
If there's more complicated logic for a given hardware,
the card driver may eventually export a new read-only
sound control for the LED group and do the logic itself.

The new LED trigger control code is completely separated
and possibly optional (there's no symbol dependency).
The full code separation allows eventually to move this
LED trigger control to the user space in future.
Actually it replaces the already present functionality
in the kernel space (HDA drivers) and allows a quick adoption
for the recent hardware (ASoC codecs including SoundWire).

snd_ctl_led            24576  0

The sound driver implementation is really easy:

1) call snd_ctl_led_request() when control LED layer should be
   automatically activated
   / it calls module_request("snd-ctl-led") on demand /
2) mark all related kcontrols with
        SNDRV_CTL_ELEM_ACCESS_SPK_LED or
        SNDRV_CTL_ELEM_ACCESS_MIC_LED

Link: https://lore.kernel.org/r/20210317172945.842280-1-perex@perex.cz
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 10 insertions, 2 deletions

diff --git a/include/net/red.h b/include/net/red.h
index 932f0d79d60c..0b39eff1d50a 100644
--- a/include/net/red.h
+++ b/include/net/red.h
@@ -168,7 +168,8 @@ static inline void red_set_vars(struct red_vars *v)
 	v->qcount	= -1;
 }
 
-static inline bool red_check_params(u32 qth_min, u32 qth_max, u8 Wlog, u8 Scell_log)
+static inline bool red_check_params(u32 qth_min, u32 qth_max, u8 Wlog,
+				    u8 Scell_log, u8 *stab)
 {
 	if (fls(qth_min) + Wlog > 32)
 		return false;
@@ -178,6 +179,13 @@ static inline bool red_check_params(u32 qth_min, u32 qth_max, u8 Wlog, u8 Scell_
 		return false;
 	if (qth_max < qth_min)
 		return false;
+	if (stab) {
+		int i;
+
+		for (i = 0; i < RED_STAB_SIZE; i++)
+			if (stab[i] >= 32)
+				return false;
+	}
 	return true;
 }
 
@@ -287,7 +295,7 @@ static inline unsigned long red_calc_qavg_from_idle_time(const struct red_parms
 	int  shift;
 
 	/*
-	 * The problem: ideally, average length queue recalcultion should
+	 * The problem: ideally, average length queue recalculation should
 	 * be done over constant clock intervals. This is too expensive, so
 	 * that the calculation is driven by outgoing packets.
 	 * When the queue is idle we have to model this clock by hand.