Re: [PATCH] ALSA: usb-audio: Fix parameter block size for UAC2 control requests

[Takashi Iwai <tiwai@suse.de>]

On Thu, 13 Aug 2015 13:04:46 +0200,
Julian Scheel wrote:
> 
> USB Audio Class version 2.0 supports three different parameter block sizes for
> CUR requests, which are 1 byte (5.2.3.1 Layout 1 Parameter Block), 2 bytes
> (5.2.3.2 Layout 2 Parameter Block) and 4 bytes (5.2.3.3 Layout 3 Parameter
> Block). Use the correct size according to the specific control as it was
> already done for UACv1. The allocated block size for control requests is
> increased to support the 4 byte worst case.
> 
> Signed-off-by: Julian Scheel <julian@jusst.de>
> ---
>  sound/usb/mixer.c | 83 +++++++++++++++++++++++++++++++++++++++++--------------
>  sound/usb/mixer.h |  2 ++
>  2 files changed, 65 insertions(+), 20 deletions(-)
> 
> diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> index 4a49944..675725b 100644
> --- a/sound/usb/mixer.c
> +++ b/sound/usb/mixer.c
> @@ -233,6 +233,14 @@ static int convert_signed_value(struct usb_mixer_elem_info *cval, int val)
>  		if (val >= 0x8000)
>  			val -= 0x10000;
>  		break;
> +	case USB_MIXER_U32:
> +		val &= 0xffffffff;
> +		break;
> +	case USB_MIXER_S32:
> +		val &= 0xffffffff;
> +		if (val >= 0x80000000)
> +			val -= 0x100000000;
> +		break;

All these are superfluous, as int on Linux is always 32bit.


>  	}
>  	return val;
>  }
> @@ -253,6 +261,9 @@ static int convert_bytes_value(struct usb_mixer_elem_info *cval, int val)
>  	case USB_MIXER_S16:
>  	case USB_MIXER_U16:
>  		return val & 0xffff;
> +	case USB_MIXER_S32:
> +	case USB_MIXER_U32:
> +		return val & 0xffffffff;

Ditto.


>  	}
>  	return 0; /* not reached */
>  }
> @@ -328,14 +339,26 @@ static int get_ctl_value_v2(struct usb_mixer_elem_info *cval, int request,
>  			    int validx, int *value_ret)
>  {
>  	struct snd_usb_audio *chip = cval->head.mixer->chip;
> -	unsigned char buf[2 + 3 * sizeof(__u16)]; /* enough space for one range */
> +	unsigned char buf[4 + 3 * sizeof(__u32)]; /* enough space for one range */
>  	unsigned char *val;
>  	int idx = 0, ret, size;
>  	__u8 bRequest;
>  
>  	if (request == UAC_GET_CUR) {
>  		bRequest = UAC2_CS_CUR;
> -		size = sizeof(__u16);
> +		switch (cval->val_type) {
> +			case USB_MIXER_S32:
> +			case USB_MIXER_U32:
> +				size = 4;
> +				break;
> +			case USB_MIXER_S16:
> +			case USB_MIXER_U16:
> +				size = 2;
> +				break;
> +			default:
> +				size = 1;
> +				break;

Please split this into a small helper function,
e.g. uac2_ctl_value_size().  The same stuff is used in below, too.

> +		}
>  	} else {
>  		bRequest = UAC2_CS_RANGE;
>  		size = sizeof(buf);
> @@ -446,7 +469,7 @@ int snd_usb_mixer_set_ctl_value(struct usb_mixer_elem_info *cval,
>  				int request, int validx, int value_set)
>  {
>  	struct snd_usb_audio *chip = cval->head.mixer->chip;
> -	unsigned char buf[2];
> +	unsigned char buf[4];
>  	int idx = 0, val_len, err, timeout = 10;
>  
>  	validx += cval->idx_off;
> @@ -454,8 +477,19 @@ int snd_usb_mixer_set_ctl_value(struct usb_mixer_elem_info *cval,
>  	if (cval->head.mixer->protocol == UAC_VERSION_1) {
>  		val_len = cval->val_type >= USB_MIXER_S16 ? 2 : 1;
>  	} else { /* UAC_VERSION_2 */
> -		/* audio class v2 controls are always 2 bytes in size */
> -		val_len = sizeof(__u16);
> +		switch (cval->val_type) {
> +			case USB_MIXER_S32:
> +			case USB_MIXER_U32:
> +				val_len = 4;
> +				break;
> +			case USB_MIXER_S16:
> +			case USB_MIXER_U16:
> +				val_len = 2;
> +				break;
> +			default:
> +				val_len = 1;
> +				break;
> +		}
>  
>  		/* FIXME */
>  		if (request != UAC_SET_CUR) {
> @@ -469,6 +503,8 @@ int snd_usb_mixer_set_ctl_value(struct usb_mixer_elem_info *cval,
>  	value_set = convert_bytes_value(cval, value_set);
>  	buf[0] = value_set & 0xff;
>  	buf[1] = (value_set >> 8) & 0xff;
> +	buf[2] = (value_set >> 16) & 0xff;
> +	buf[3] = (value_set >> 24) & 0xff;

It's not smart but OK, just a subtle matter...

>  	err = snd_usb_autoresume(chip);
>  	if (err < 0)
>  		return -EIO;
> @@ -799,24 +835,25 @@ static int check_input_term(struct mixer_build *state, int id,
>  /* feature unit control information */
>  struct usb_feature_control_info {
>  	const char *name;
> -	unsigned int type;	/* control type (mute, volume, etc.) */
> +	int type;	/* data type for uac1 */
> +	int type_uac2;	/* data type for uac2 if different from uac1, else -1 */
>  };
>  
>  static struct usb_feature_control_info audio_feature_info[] = {
> -	{ "Mute",			USB_MIXER_INV_BOOLEAN },
> -	{ "Volume",			USB_MIXER_S16 },
> -	{ "Tone Control - Bass",	USB_MIXER_S8 },
> -	{ "Tone Control - Mid",		USB_MIXER_S8 },
> -	{ "Tone Control - Treble",	USB_MIXER_S8 },
> -	{ "Graphic Equalizer",		USB_MIXER_S8 }, /* FIXME: not implemeted yet */
> -	{ "Auto Gain Control",		USB_MIXER_BOOLEAN },
> -	{ "Delay Control",		USB_MIXER_U16 }, /* FIXME: U32 in UAC2 */
> -	{ "Bass Boost",			USB_MIXER_BOOLEAN },
> -	{ "Loudness",			USB_MIXER_BOOLEAN },
> +	{ "Mute",			USB_MIXER_INV_BOOLEAN, -1 },
> +	{ "Volume",			USB_MIXER_S16, -1 },
> +	{ "Tone Control - Bass",	USB_MIXER_S8, -1 },
> +	{ "Tone Control - Mid",		USB_MIXER_S8, -1 },
> +	{ "Tone Control - Treble",	USB_MIXER_S8, -1 },
> +	{ "Graphic Equalizer",		USB_MIXER_S8, -1 }, /* FIXME: not implemeted yet */
> +	{ "Auto Gain Control",		USB_MIXER_BOOLEAN, -1 },
> +	{ "Delay Control",		USB_MIXER_U16, USB_MIXER_U32 },
> +	{ "Bass Boost",			USB_MIXER_BOOLEAN, -1 },
> +	{ "Loudness",			USB_MIXER_BOOLEAN, -1 },
>  	/* UAC2 specific */
> -	{ "Input Gain Control",		USB_MIXER_S16 },
> -	{ "Input Gain Pad Control",	USB_MIXER_S16 },
> -	{ "Phase Inverter Control",	USB_MIXER_BOOLEAN },
> +	{ "Input Gain Control",		USB_MIXER_S16, -1 },
> +	{ "Input Gain Pad Control",	USB_MIXER_S16, -1 },
> +	{ "Phase Inverter Control",	USB_MIXER_BOOLEAN, -1 },
>  };
>  
>  /* private_free callback */
> @@ -1241,7 +1278,13 @@ static void build_feature_ctl(struct mixer_build *state, void *raw_desc,
>  	snd_usb_mixer_elem_init_std(&cval->head, state->mixer, unitid);
>  	cval->control = control;
>  	cval->cmask = ctl_mask;
> -	cval->val_type = audio_feature_info[control-1].type;
> +	if (state->mixer->protocol == UAC_VERSION_1)
> +		cval->val_type = audio_feature_info[control-1].type;
> +	else /* UAC_VERSION_2 */
> +		cval->val_type = audio_feature_info[control-1].type_uac2 > -1 ?

Usually ">= 0" is used.

> +			audio_feature_info[control-1].type_uac2 :
> +			audio_feature_info[control-1].type;

Since audio_feature_info[control-1] is referred so many times, it's
better to put in a temporary variable.


thanks,

Takashi