[alsa-devel] Lost dB volumes on USB headset between 2.6.38 and 3.0

[Takashi Iwai]

At Tue, 09 Aug 2011 13:19:37 +0200,
Colin Guthrie wrote:
> 
> 'Twas brillig, and Clemens Ladisch at 09/08/11 12:39 did gyre and gimble:
> > David Henningsson wrote:
> >> Hmm, I and Colin Guthrie have found a regression between kernels 2.6.38
> >> and 3.0.
> >>
> >> When running "amixer -D hw:handset" for this device under 2.6.38, the
> >> attached file is returned. Under 3.0, the dB information is missing.
> >> This can't be intentional, can it?
> > 
> > There are patches that might have introduced bugs, but these two patches
> > do remove dB information intentionally:
> > 
> > ALSA: usb-audio - Don't expose broken dB ranges:
> > http://git.alsa-project.org/?p=alsa-kernel.git;a=commitdiff;h=59bb7f0eebe6
> > ALSA: usb-audio - Add volume range check and warn if it too big:
> > http://git.alsa-project.org/?p=alsa-kernel.git;a=commitdiff;h=80acefff3bc7
> > 
> > Are there any messages in the system log when loading the driver?
> > What are the controls' dB ranges (see "amixer contents")?
> 
> Interesting thanks fpr the hints.
> 
> I get this when plugging in the device David mentioned previously.
> 
> 
> usb 3-1: USB disconnect, device number 2
> usbcore: deregistering interface driver snd-usb-audio
> usb 2-1: new full speed USB device number 7 using uhci_hcd
> usb 2-1: New USB device found, idVendor=1885, idProduct=0501
> usb 2-1: New USB device strings: Mfr=2, Product=1, SerialNumber=0
> usb 2-1: Product: BT Agile handset
> usb 2-1: Manufacturer: Ascalade
> input: Ascalade BT Agile handset as
> /devices/pci0000:00/0000:00:1d.1/usb2/2-1/2-1:1.3/input/input14
> generic-usb 0003:1885:0501.0006: input,hidraw0: USB HID v1.00 Device
> [Ascalade BT Agile handset] on usb-0000:00:1d.1-1/input3
> 13:0: cannot get min/max values for control 2 (id 13)
> 14:0: cannot get min/max values for control 2 (id 14)
> 9:0: cannot get min/max values for control 2 (id 9)
> 10:0: cannot get min/max values for control 2 (id 10)
> 11:0: cannot get min/max values for control 2 (id 11)
> 9:0: cannot get min/max values for control 2 (id 9)
> 14:0: cannot get min/max values for control 2 (id 14)
> 11:0: cannot get min/max values for control 2 (id 11)
> 13:0: cannot get min/max values for control 2 (id 13)
> 10:0: cannot get min/max values for control 2 (id 10)
> 9:0: cannot get min/max values for control 2 (id 9)

So the problem is that the driver can't extract the dB values.
If the problem is seen only at the beginning of driver initialization,
the patch below may work.

Also, could you give "lsusb -v" output, too?


Takashi

---
diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index c04d7c7..cdd19d7 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -152,6 +152,7 @@ static inline void check_mapped_dB(const struct usbmix_name_map *p,
 	if (p && p->dB) {
 		cval->dBmin = p->dB->min;
 		cval->dBmax = p->dB->max;
+		cval->initialized = 1;
 	}
 }
 
@@ -1092,7 +1093,7 @@ static void build_feature_ctl(struct mixer_build *state, void *raw_desc,
 				" Switch" : " Volume");
 		if (control == UAC_FU_VOLUME) {
 			check_mapped_dB(map, cval);
-			if (cval->dBmin < cval->dBmax) {
+			if (cval->dBmin < cval->dBmax || !cval->initialized) {
 				kctl->tlv.c = mixer_vol_tlv;
 				kctl->vd[0].access |= 
 					SNDRV_CTL_ELEM_ACCESS_TLV_READ |