On Fri, 08 Apr 2016 19:52:01 +0200, Daniel Mack wrote:
UAC2 specifies clock sources that optionally have validity controls. This patch exposes them as mixer controls, so they can be read (and at least in theory even be written) by userspace applications in order to make clock selection policy decisions.
This implementation does nothing if the device is not UAC2 compliant, or if the clock source does not define said validity control bits.
Tested with a miniDSP USBStreamer (0x2752/0x0016),
Signed-off-by: Daniel Mack daniel@zonque.org
sound/usb/mixer.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 65 insertions(+), 1 deletion(-)
diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c index 4f85757..973274b 100644 --- a/sound/usb/mixer.c +++ b/sound/usb/mixer.c @@ -45,6 +45,7 @@ #include <linux/bitops.h> #include <linux/init.h> #include <linux/list.h> +#include <linux/log2.h> #include <linux/slab.h> #include <linux/string.h> #include <linux/usb.h> @@ -1378,6 +1379,68 @@ static void build_feature_ctl(struct mixer_build *state, void *raw_desc, snd_usb_mixer_add_control(&cval->head, kctl); }
+static int parse_clock_source_unit(struct mixer_build *state, int unitid,
void *_ftr)+{
- struct uac_clock_source_descriptor *hdr = _ftr;
- struct usb_mixer_elem_info *cval;
- struct snd_kcontrol *kctl;
- char name[100];
No need for 100. SNDRV_CTL_ELEM_ID_NAME_MAXLEN should suffice.
- int ret;
- if (state->mixer->protocol != UAC_VERSION_2)
return -EINVAL;- if (hdr->bLength != sizeof(*hdr))
return -EINVAL;
I wonder whether we should abort here and return an error. It's a wacky firmware, and no kernel error, after all.
- /*
* The only property of this unit we are interested in is the* clock source validity. If that isn't readable, just bail out.*/- if (!uac2_control_is_readable(hdr->bmControls,
ilog2(UAC2_CS_CONTROL_CLOCK_VALID)))return 0;- cval = kzalloc(sizeof(*cval), GFP_KERNEL);
- if (!cval)
return -ENOMEM;- snd_usb_mixer_elem_init_std(&cval->head, state->mixer, hdr->bClockID);
- cval->min = 0;
- cval->max = 1;
- cval->channels = 1;
- cval->val_type = USB_MIXER_BOOLEAN;
- cval->control = UAC2_CS_CONTROL_CLOCK_VALID;
- if (uac2_control_is_writeable(hdr->bmControls,
ilog2(UAC2_CS_CONTROL_CLOCK_VALID)))kctl = snd_ctl_new1(&usb_feature_unit_ctl, cval);- else {
cval->master_readonly = 1;kctl = snd_ctl_new1(&usb_feature_unit_ctl_ro, cval);- }
- if (!kctl) {
kfree(cval);return -ENOMEM;- }
- kctl->private_free = snd_usb_mixer_elem_free;
- ret = snd_usb_copy_string_desc(state, hdr->iClockSource,
name, sizeof(name));- if (ret > 0)
snprintf(kctl->id.name, sizeof(kctl->id.name),"%s validity", name);- else
snprintf(kctl->id.name, sizeof(kctl->id.name),"Clock source %d validity", hdr->bClockID);
Each word in control name is usually starting with a capital letter.
thanks,
Takashi