On Fri, Jul 12, 2024 at 08:20:26PM -0600, Mark Hesselink wrote:
> Hi,
> 
> jca suggested I sent the below email to tech@ instead of misc@ with ratchov@ on Cc.
> 
> ---
> 
> I recently bought a JBL USB-C wired headphones for my 2020 Apple MacBook Air to enjoy audio without disturbing my family. The headphones is exposed via uaudio(4) as audio1 to the system. The headphones come with a simple consumer control keyboard supported by ucc(4) and wskbd(4). The keyboard exposes 2 volume control keys and an unmapped key. The relevant dmesg(8) lines are:
> 
> uaudio0 at uhub1 port 1 configuration 1 interface 1 "KTMICRO JBL TUNE 310C USB-C" rev 2.00/0.03 addr 2
> uaudio0: class v1, full-speed, sync, channels: 2 play, 1 rec, 5 ctls
> audio1 at uaudio0
> uhidev0 at uhub1 port 1 configuration 1 interface 3 "KTMICRO JBL TUNE 310C USB-C" rev 2.00/0.03 addr 2
> uhidev0: iclass 3/0, 84 report ids
> ucc0 at uhidev0 reportid 1: 4 usages, 3 keys, enum
> wskbd1 at ucc0 mux 1
> wskbd1: connecting to wsdisplay0
> uhid0 at uhidev0 reportid 75: input=10, output=10, feature=0
> uhid1 at uhidev0 reportid 84: input=10, output=10, feature=0
> 
> The volume control keys unfortunately can only control audio0 in an OpenBSD 7.5-stable system as sys/dev/hid/hidcc.c does not currently pass the audio cookie it receives from ucc(4) on to wskbd(4). The attached hidcc_c.patch is a (simple) attempt at fixing this issue. It allows me to control the volume on my headphones using the consumer control keyboard, a good quality of life improvement.

I disabled ucc audio support after caspar@ reported an interrupt storm
after pressing the volume keys on some headset. I was never able to
reproduce the problem with my hardware and I don't think caspar@ managed
to root cause it either.

> Cheers,
> 
> Mark

> Index: dev/hid/hidcc.c
> ===================================================================
> RCS file: /cvs/src/sys/dev/hid/hidcc.c,v
> diff -u -r1.5 hidcc.c
> --- dev/hid/hidcc.c	14 Nov 2022 00:16:44 -0000	1.5
> +++ dev/hid/hidcc.c	7 Jul 2024 15:42:13 -0000
> @@ -593,7 +593,7 @@
>  #undef N
>  };
>  
> -void	hidcc_attach_wskbd(struct hidcc *);
> +void	hidcc_attach_wskbd(struct hidcc *, void *);
>  int	hidcc_enable(void *, int);
>  void	hidcc_set_leds(void *, int);
>  int	hidcc_ioctl(void *, u_long, caddr_t, int, struct proc *);
> @@ -667,7 +667,7 @@
>  
>  	/* Cannot load an empty map. */
>  	if (sc->sc_maplen > 0)
> -		hidcc_attach_wskbd(sc);
> +		hidcc_attach_wskbd(sc, hca->audio_cookie);
>  
>  	return sc;
>  }
> @@ -755,7 +755,7 @@
>  }
>  
>  void
> -hidcc_attach_wskbd(struct hidcc *sc)
> +hidcc_attach_wskbd(struct hidcc *sc, void *audio_cookie)
>  {
>  	static const struct wskbd_accessops accessops = {
>  		.enable		= hidcc_enable,
> @@ -767,7 +767,7 @@
>  		.keymap		= &sc->sc_keymap,
>  		.accessops	= &accessops,
>  		.accesscookie	= sc,
> -		.audiocookie	= NULL,	/* XXX audio_cookie */
> +		.audiocookie	= audio_cookie
>  	};
>  
>  	sc->sc_keydesc[0].name = KB_US;