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SubjectRe: [PATCH 1/4] ALSA: usb-audio: UAC3. Add support for mixer unit.
On Fri, 20 Apr 2018 19:03:24 +0200,
Jorge Sanjuan wrote:
>
> This adds support for the MIXER UNIT in UAC3. All the information
> is obtained from the (HIGH CAPABILITY) Cluster's header. We don't
> read the rest of the logical cluster to obtain the channel config
> as that wont make any difference in the current mixer behaviour.
>
> The name of the mixer unit is not yet requested as there is not
> support for the UAC3 Class Specific String requests.
>
> Tested in an UAC3 device working as a HEADSET with a basic mixer
> unit (same as the one in the BADD spec) with no controls.
>
> Signed-off-by: Jorge Sanjuan <jorge.sanjuan@codethink.co.uk>
> ---
> include/uapi/linux/usb/audio.h | 13 +++++++--
> sound/usb/mixer.c | 64 ++++++++++++++++++++++++++++++++++++++++--
> 2 files changed, 71 insertions(+), 6 deletions(-)
>
> diff --git a/include/uapi/linux/usb/audio.h b/include/uapi/linux/usb/audio.h
> index 3a78e7145689..f9be472cd025 100644
> --- a/include/uapi/linux/usb/audio.h
> +++ b/include/uapi/linux/usb/audio.h
> @@ -285,9 +285,16 @@ static inline __u8 uac_mixer_unit_iChannelNames(struct uac_mixer_unit_descriptor
> static inline __u8 *uac_mixer_unit_bmControls(struct uac_mixer_unit_descriptor *desc,
> int protocol)
> {
> - return (protocol == UAC_VERSION_1) ?
> - &desc->baSourceID[desc->bNrInPins + 4] :
> - &desc->baSourceID[desc->bNrInPins + 6];
> + switch (protocol) {
> + case UAC_VERSION_1:
> + return &desc->baSourceID[desc->bNrInPins + 4];
> + case UAC_VERSION_2:
> + return &desc->baSourceID[desc->bNrInPins + 6];
> + case UAC_VERSION_3:
> + return &desc->baSourceID[desc->bNrInPins + 2];
> + default:
> + return NULL;
> + }
> }
>
> static inline __u8 uac_mixer_unit_iMixer(struct uac_mixer_unit_descriptor *desc)
> diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
> index 301ad61ed426..738ca37e6d6e 100644
> --- a/sound/usb/mixer.c
> +++ b/sound/usb/mixer.c
> @@ -719,6 +719,35 @@ static int get_term_name(struct mixer_build *state, struct usb_audio_term *iterm
> }
>
> /*
> + * Get logical cluster information for UAC3 devices.
> + */
> +static int get_cluster_channels_v3(struct mixer_build *state, unsigned int cluster_id)
> +{
> + struct uac3_cluster_header_descriptor c_header;
> + int err;
> +
> + err = snd_usb_ctl_msg(state->chip->dev,
> + usb_rcvctrlpipe(state->chip->dev, 0),
> + UAC3_CS_REQ_HIGH_CAPABILITY_DESCRIPTOR,
> + USB_RECIP_INTERFACE | USB_TYPE_CLASS | USB_DIR_IN,
> + cluster_id,
> + snd_usb_ctrl_intf(state->chip),
> + &c_header, sizeof(c_header));
> + if (err < 0)
> + goto error;
> + else if (err != sizeof(c_header)) {
> + err = -EIO;
> + goto error;
> + }

Try to balance to put braces in both if and else.
In this case, though, you can just do like below, too:

if (err < 0)
goto error;
if (err != sizeof(c_header)) {
err = -EIO;
goto error;
}


> +
> + return c_header.bNrChannels;
> +
> +error:
> + usb_audio_err(state->chip, "cannot request logical cluster ID: %d (err: %d)\n", cluster_id, err);
> + return err;
> +}
> +
> +/*
> * parse the source unit recursively until it reaches to a terminal
> * or a branched unit.
> */
> @@ -865,6 +894,19 @@ static int check_input_term(struct mixer_build *state, int id,
> term->name = le16_to_cpu(d->wClockSourceStr);
> return 0;
> }
> + case UAC3_MIXER_UNIT: {
> + struct uac_mixer_unit_descriptor *d = p1;
> + unsigned int cluster_id = le16_to_cpu(d->baSourceID[d->bNrInPins]);
> +
> + err = get_cluster_channels_v3(state, cluster_id);
> + if (err < 0)
> + return err;
> +
> + term->channels = err;
> + term->type = d->bDescriptorSubtype << 16; /* virtual type */
> +
> + return 0;
> + }
> default:
> return -ENODEV;
> }
> @@ -1801,7 +1843,7 @@ static void build_mixer_unit_ctl(struct mixer_build *state,
> struct usb_audio_term *iterm)
> {
> struct usb_mixer_elem_info *cval;
> - unsigned int num_outs = uac_mixer_unit_bNrChannels(desc);
> + unsigned int num_outs;
> unsigned int i, len;
> struct snd_kcontrol *kctl;
> const struct usbmix_name_map *map;
> @@ -1814,6 +1856,14 @@ static void build_mixer_unit_ctl(struct mixer_build *state,
> if (!cval)
> return;
>
> + if (state->mixer->protocol == UAC_VERSION_3) {
> + num_outs = get_cluster_channels_v3(state,
> + le16_to_cpu(desc->baSourceID[desc->bNrInPins]));
> + if (num_outs < 0)
> + return;
> + } else /* UAC_VERSION_1/2 */
> + num_outs = uac_mixer_unit_bNrChannels(desc);
> +
> snd_usb_mixer_elem_init_std(&cval->head, state->mixer, unitid);
> cval->control = in_ch + 1; /* based on 1 */
> cval->val_type = USB_MIXER_S16;
> @@ -1878,8 +1928,16 @@ static int parse_audio_mixer_unit(struct mixer_build *state, int unitid,
> int input_pins, num_ins, num_outs;
> int pin, ich, err;
>
> - if (desc->bLength < 11 || !(input_pins = desc->bNrInPins) ||
> - !(num_outs = uac_mixer_unit_bNrChannels(desc))) {
> + if (state->mixer->protocol == UAC_VERSION_3) {
> + err = get_cluster_channels_v3(state,
> + le16_to_cpu(desc->baSourceID[desc->bNrInPins]));
> + if (err < 0)
> + return err;
> + num_outs = err;
> + } else /* UAC_VERSION_1/2 */
> + num_outs = uac_mixer_unit_bNrChannels(desc);

These three calls are all similar. Maybe it'd be cleaner if you
introduce another helper to get the channels for MU?

static int uac_mixer_unit_get_channels(struct mixer_build *state,
struct uac_mixer_unit_descriptor *desc)
{
int input_pins;
int num_outs;

if (desc->bLength < 11)
return -EINVAL;
input_pins = desc->bNrInPins;
if (!input_pins)
return -EINVAL;

switch (state->mixer->protocol) {
case UAC_VERSION_1:
case UAC_VERSION_2:
default:
channels = uac_mixer_unit_bNrChannels(desc);
break;
case UAC_VERSION_3:
channels = get_cluster_channels_v3(state,
le16_to_cpu(desc->baSourceID[]);
break;
}
if (!channels)
return -EINVAL;
return channels;
}

And, as you can see in the above, you have to do the length check
before actually accessing the descriptor's field.


thanks,

Takashi
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