[PATCH 16/31] ALSA: usb-audio: scarlett2: Add Gen 3 mixer support

[Takashi Iwai]

On Tue, 22 Jun 2021 09:07:20 +0200,
Vladimir Sadovnikov wrote:
> 
> Hello Takashi!
> 
> Since Focusrite devices are too advanced in settings, the overall
> amount of 256 controls is not enough for these devices (like 18i20).
> I would like also to extend this constant up to 1024 or even more
> since adding support of software configuration of the device also
> can exceed the amount of 512 control elements.

This define isn't for the total number of mixer elements.  Instead,
it's just a size of the bitmap table that contains the head of the
linked list for each unit id (in the sense of USB mixer spec).
So the number of mixer elements is unlimited.


Takashi

> 
> Let's assume we have a mute switch for each mixer gain setting. For
> the 18i20 device this will give:
> 12 inputs * 25 outputs = 300 mute switches.
> 
> So I think this constant should be increased rapidly up to 1024 or even to 2048.
> 
> Best,
> Vladimir
> 
> 22.06.2021 10:00, Takashi Iwai пишет:
> > On Mon, 21 Jun 2021 20:09:48 +0200,
> > Geoffrey D. Bennett wrote:
> >> Add mixer support for the Focusrite Scarlett 4i4, 8i6, 18i8, and 18i20
> >> Gen 3 devices.
> >>
> >> Signed-off-by: Geoffrey D. Bennett <g at b4.vu>
> >> ---
> >>   sound/usb/mixer.c               |   2 +-
> >>   sound/usb/mixer_quirks.c        |   4 +
> >>   sound/usb/mixer_scarlett_gen2.c | 260 +++++++++++++++++++++++++++++---
> >>   3 files changed, 246 insertions(+), 20 deletions(-)
> >>
> >> diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> >> index 428d581f988f..ba4aa1eacb04 100644
> >> --- a/sound/usb/mixer.c
> >> +++ b/sound/usb/mixer.c
> >> @@ -50,7 +50,7 @@
> >>   #include "mixer_quirks.h"
> >>   #include "power.h"
> >>   -#define MAX_ID_ELEMS	256
> >> +#define MAX_ID_ELEMS	512
> > This change requires the explanation.
> > Usually the unit id is a byte per definition, so it can't be over
> > 256.
> >
> >
> > thanks,
> >
> > Takashi
> 
>