Re: [alsa-devel] [PATCH 4/4] ALSA: usb: add UAC3 BADD profiles support

From: Ruslan Bilovol
Date: Tue Apr 24 2018 - 03:51:54 EST


On Thu, Apr 19, 2018 at 1:19 PM, Takashi Iwai <tiwai@xxxxxxx> wrote:
> On Sat, 14 Apr 2018 00:24:26 +0200,
> Ruslan Bilovol wrote:
>>
>> +static void build_feature_ctl_badd(struct usb_mixer_interface *mixer,
>> + unsigned int ctl_mask, int control, int unitid,
>> + const struct usbmix_name_map *badd_map)
>> +{
> ....
>> + kctl = snd_ctl_new1(&usb_feature_unit_ctl, cval);
>> +
>> + if (!kctl) {
>> + usb_audio_err(mixer->chip, "cannot malloc kcontrol\n");
>
> No need for error message after malloc failure. The kernel is already
> chatty about it.

Okay. BTW, I'm trying to avoid separate badd variant of
build_feature_ctl(), so this most probably will go away.

There are many existing places in usb-snd which can be cleaned
up though.

>
>
>> +static int snd_usb_mixer_controls_badd(struct usb_mixer_interface *mixer,
>> + int ctrlif)
>> +{
>> + struct usb_device *dev = mixer->chip->dev;
>> + struct usb_interface_assoc_descriptor *assoc;
>> + int badd_profile = mixer->chip->badd_profile;
>> + const struct usbmix_ctl_map *map;
>> + int p_chmask = 0, c_chmask = 0, st_chmask = 0;
>> + int i;
>> +
>> + assoc = usb_ifnum_to_if(dev, ctrlif)->intf_assoc;
>> +
>> + /* Detect BADD capture/playback channels from AS EP descriptors */
>> + for (i = 0; i < assoc->bInterfaceCount; i++) {
>> + int intf = assoc->bFirstInterface + i;
>> +
>> + if (intf != ctrlif) {
>
> In this case, it's better to skip like
>
> if (intf == ctrlif)
> continue;
>
> so that we can save an indentation for the whole long block.

Good point, will do it

>
>> + switch (badd_profile) {
>> + default:
>> + return -EINVAL;
>> + case UAC3_FUNCTION_SUBCLASS_GENERIC_IO:
>> + /*
>> + * BAIF, BAOF or combination of both
>> + * IN: Mono or Stereo cfg, Mono alt possible
>> + * OUT: Mono or Stereo cfg, Mono alt possible
>> + */
>> + /* c_chmask := DYNAMIC */
>> + /* p_chmask := DYNAMIC */
>> + if (!c_chmask && !p_chmask) {
>> + usb_audio_err(mixer->chip,
>> + "BADD GENERIC_IO profile: no channels?\n");
>> + return -EINVAL;
>> + }
>> + break;
>
> Maybe we can simplify the whole switch/case with a table lookup.

Yes, it should be possible, I'll implent it that way

Thanks,
Ruslan

> For example,
>
> for (f = uac3_func_tables; f->name; f++) {
> if (badd_profile == f->subclass)
> break;
> }
> if (!f->name)
> return -EINVAL;
> if (!uac3_func_has_valid_channels(mixer, f, c_chmask, p_chmask))
> return -EINVAL;
> st_chmask = f->st_chmask;
>
> and in uac3_func_has_valid_channels(),
>
> static bool uac3_func_has_valid_channels()
> {
> if ((f->c_chmask < 0 && !c_chmask) ||
> (f->c_chmask >= 0 && f->c_chmask != c_chmask)) {
> usb_audio_warn(mixer->chip, "BAAD %s c_chmask mismatch",
> f->name);
> return false;
> }
> if ((f->p_chmask < 0 && !p_chmask) ||
> (f->p_chmask >= 0 && f->p_chmask != p_chmask)) {
> usb_audio_warn(mixer->chip, "BAAD %s p_chmask mismatch",
> f->name);
> return false;
> }
> return true;
> }
>
>
> thanks,
>
> Takashi