[alsa-devel] Quirk to disable master volume control in PCM2702
[Alan Stern on BCC]
Hi ALSA developers,
I've written the attached patch to disable the master volume control in this chipset. The datasheet [1] documents two independent channel volume controls, one master mute control and one master volume control. However, at least on my device (a Fubar USB DAC), the master volume control always returns USB stalls when queried for any of its parameters (min/max/res/cur). All other controls work as expected, both at the protocol and at the application levels.
Read on for the gory details. Otherwise please take the patch at face value. I'm ready to make changes if necessary to make it more fitting to the rest of the code. It would be very appreciated if this can go into 2.6.32, or in a stable patch shortly after.
Normally I wouldn't give this problem a second thought, since in the worst case a non-functional control appears in the mixer. Only that Alan Stern submitted a patch to the USB subsystem during the development of kernel 2.6.31 that enables the sending of the Clear-TT-Buffer request to USB hubs on stalls from devices. For some reason upon receiving the Clear-TT-Buffer the audio goes mute, even though the kernel keeps sending the audio stream to the device. There is an ongoing thread on the linux-usb ML where Alan argues that sending the request is the correct behavior and it shouldn't have the effect I'm seeing. Since I lack any knowledge of the USB protocol, I take his word. However, it seems that either the USB specs are wrong, or my USB hub or the card are buggy.
In the meantime I'm trying to get another hub to compare. Unfortunately I have to rely on the hub, because the PCM2702 and my motherboard don't interact well. After a while the sound is degraded, first into a hiss, then into pure noise. Other users have complained on different forums; one of the wrote to alsa-user a month ago. I haven't been able to make any progress to track this issue with usbmon and ALSA verbose debug messages, to nobody's surprise, since I'm a complete layman in that area. Any help with this would be appreciated as well.
[1] http://focus.ti.com/docs/prod/folders/print/pcm2702.html
Javier Kohen wrote:
I've written the attached patch to disable the master volume control in this chipset. The datasheet [1] documents two independent channel volume controls, one master mute control and one master volume control. However, at least on my device (a Fubar USB DAC), the master volume control always returns USB stalls when queried for any of its parameters (min/max/res/cur).
I'd guess that Windows ignores the master volume when it finds channel volume controls, so this function was never actually tested.
However, it seems that either the USB specs are wrong,
They are abominations written by committees.
or my USB hub or the card are buggy.
Your hub is certainly buggy ...
the PCM2702 and my motherboard don't interact well. After a while the sound is degraded, first into a hiss, then into pure noise.
... the card too.
Your patch looks good; please provide a log message and a Signed-off-by tag.
Best regards, Clemens
Clemens,
On Tue, Nov 17, 2009 at 10:04, Clemens Ladisch clemens@ladisch.de wrote:
Javier Kohen wrote:
I've written the attached patch to disable the master volume control in this chipset. The datasheet [1] documents two independent channel volume controls, one master mute control and one master volume control. However, at least on my device (a Fubar USB DAC), the master volume control always returns USB stalls when queried for any of its parameters (min/max/res/cur).
I'd guess that Windows ignores the master volume when it finds channel volume controls, so this function was never actually tested.
However, it seems that either the USB specs are wrong,
They are abominations written by committees.
or my USB hub or the card are buggy.
Your hub is certainly buggy ...
the PCM2702 and my motherboard don't interact well. After a while the sound is degraded, first into a hiss, then into pure noise.
... the card too.
Your patch looks good; please provide a log message and a Signed-off-by tag.
Thanks for the prompt review!
Disable the master volume control in the PCM2702 chipset.
The datasheet documents two independent channel volume controls, one master mute control and one master volume control. All controls are fully functional except for the master volume control, which returns USB stalls on all GET requests.
Signed-off-by: Javier Kohen jkohen@users.sourceforge.net --- diff --git a/sound/usb/usbmixer.c b/sound/usb/usbmixer.c index 9efcfd0..406315e 100644 --- a/sound/usb/usbmixer.c +++ b/sound/usb/usbmixer.c @@ -1071,6 +1071,16 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, unsig channels = (ftr[0] - 7) / csize - 1;
master_bits = snd_usb_combine_bytes(ftr + 6, csize); + /* master configuration quirks */ + switch (state->chip->usb_id) { + case USB_ID(0x08bb, 0x2702): + snd_printk(KERN_INFO + "master volume quirk for PCM2702 chip\n"); + /* disable non-functional volume control */ + master_bits &= ~(1 << (USB_FEATURE_VOLUME - 1)); + break; + + } if (channels > 0) first_ch_bits = snd_usb_combine_bytes(ftr + 6 + csize, csize); else
At Tue, 17 Nov 2009 11:59:36 +0100, Javier Kohen wrote:
Clemens,
On Tue, Nov 17, 2009 at 10:04, Clemens Ladisch clemens@ladisch.de wrote:
Javier Kohen wrote:
I've written the attached patch to disable the master volume control in this chipset. The datasheet [1] documents two independent channel volume controls, one master mute control and one master volume control. However, at least on my device (a Fubar USB DAC), the master volume control always returns USB stalls when queried for any of its parameters (min/max/res/cur).
I'd guess that Windows ignores the master volume when it finds channel volume controls, so this function was never actually tested.
However, it seems that either the USB specs are wrong,
They are abominations written by committees.
or my USB hub or the card are buggy.
Your hub is certainly buggy ...
the PCM2702 and my motherboard don't interact well. After a while the sound is degraded, first into a hiss, then into pure noise.
... the card too.
Your patch looks good; please provide a log message and a Signed-off-by tag.
Thanks for the prompt review!
Disable the master volume control in the PCM2702 chipset.
The datasheet documents two independent channel volume controls, one master mute control and one master volume control. All controls are fully functional except for the master volume control, which returns USB stalls on all GET requests.
Signed-off-by: Javier Kohen jkohen@users.sourceforge.net
diff --git a/sound/usb/usbmixer.c b/sound/usb/usbmixer.c index 9efcfd0..406315e 100644 --- a/sound/usb/usbmixer.c +++ b/sound/usb/usbmixer.c @@ -1071,6 +1071,16 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, unsig channels = (ftr[0] - 7) / csize - 1;
master_bits = snd_usb_combine_bytes(ftr + 6, csize);
- /* master configuration quirks */
- switch (state->chip->usb_id) {
- case USB_ID(0x08bb, 0x2702):
snd_printk(KERN_INFO"master volume quirk for PCM2702 chip\n");
Better to put a prefix like "usbmixer: master volume ..." since snd_printk() can be turned to the normal printk() depending on the kernel config.
thanks,
Takashi
Takashi,
On Tue, Nov 17, 2009 at 12:03, Takashi Iwai tiwai@suse.de wrote:
At Tue, 17 Nov 2009 11:59:36 +0100, Javier Kohen wrote:
Clemens,
On Tue, Nov 17, 2009 at 10:04, Clemens Ladisch clemens@ladisch.de wrote:
Javier Kohen wrote:
I've written the attached patch to disable the master volume control in this chipset. The datasheet [1] documents two independent channel volume controls, one master mute control and one master volume control. However, at least on my device (a Fubar USB DAC), the master volume control always returns USB stalls when queried for any of its parameters (min/max/res/cur).
I'd guess that Windows ignores the master volume when it finds channel volume controls, so this function was never actually tested.
However, it seems that either the USB specs are wrong,
They are abominations written by committees.
or my USB hub or the card are buggy.
Your hub is certainly buggy ...
the PCM2702 and my motherboard don't interact well. After a while the sound is degraded, first into a hiss, then into pure noise.
... the card too.
Your patch looks good; please provide a log message and a Signed-off-by tag.
Thanks for the prompt review!
Better to put a prefix like "usbmixer: master volume ..." since snd_printk() can be turned to the normal printk() depending on the kernel config.
I don't know if the comment was for me or for whoever will submit this, but here you go just in case:
Disable the master volume control in the PCM2702 chipset.
The datasheet documents two independent channel volume controls, one master mute control and one master volume control. All controls are fully functional except for the master volume control, which returns USB stalls on all GET requests.
Signed-off-by: Javier Kohen jkohen@users.sourceforge.net --- diff --git a/sound/usb/usbmixer.c b/sound/usb/usbmixer.c index 9efcfd0..406315e 100644 --- a/sound/usb/usbmixer.c +++ b/sound/usb/usbmixer.c @@ -1071,6 +1071,16 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, unsig channels = (ftr[0] - 7) / csize - 1;
master_bits = snd_usb_combine_bytes(ftr + 6, csize); + /* master configuration quirks */ + switch (state->chip->usb_id) { + case USB_ID(0x08bb, 0x2702): + snd_printk(KERN_INFO + "usbmixer: master volume quirk for PCM2702 chip\n"); + /* disable non-functional volume control */ + master_bits &= ~(1 << (USB_FEATURE_VOLUME - 1)); + break; + + } if (channels > 0) first_ch_bits = snd_usb_combine_bytes(ftr + 6 + csize, csize); else
At Tue, 17 Nov 2009 15:36:13 +0100, Javier Kohen wrote:
Takashi,
On Tue, Nov 17, 2009 at 12:03, Takashi Iwai tiwai@suse.de wrote:
At Tue, 17 Nov 2009 11:59:36 +0100, Javier Kohen wrote:
Clemens,
On Tue, Nov 17, 2009 at 10:04, Clemens Ladisch clemens@ladisch.de wrote:
Javier Kohen wrote:
I've written the attached patch to disable the master volume control in this chipset. The datasheet [1] documents two independent channel volume controls, one master mute control and one master volume control. However, at least on my device (a Fubar USB DAC), the master volume control always returns USB stalls when queried for any of its parameters (min/max/res/cur).
I'd guess that Windows ignores the master volume when it finds channel volume controls, so this function was never actually tested.
However, it seems that either the USB specs are wrong,
They are abominations written by committees.
or my USB hub or the card are buggy.
Your hub is certainly buggy ...
the PCM2702 and my motherboard don't interact well. After a while the sound is degraded, first into a hiss, then into pure noise.
... the card too.
Your patch looks good; please provide a log message and a Signed-off-by tag.
Thanks for the prompt review!
Better to put a prefix like "usbmixer: master volume ..." since snd_printk() can be turned to the normal printk() depending on the kernel config.
I don't know if the comment was for me or for whoever will submit this, but here you go just in case:
Yes, it was asked to you as the original author :)
Disable the master volume control in the PCM2702 chipset.
The datasheet documents two independent channel volume controls, one master mute control and one master volume control. All controls are fully functional except for the master volume control, which returns USB stalls on all GET requests.
Signed-off-by: Javier Kohen jkohen@users.sourceforge.net
Thanks, applied now to sound git tree. I'll include it to the next pull request for 2.6.32-final.
Takashi
diff --git a/sound/usb/usbmixer.c b/sound/usb/usbmixer.c index 9efcfd0..406315e 100644 --- a/sound/usb/usbmixer.c +++ b/sound/usb/usbmixer.c @@ -1071,6 +1071,16 @@ static int parse_audio_feature_unit(struct mixer_build *state, int unitid, unsig channels = (ftr[0] - 7) / csize - 1;
master_bits = snd_usb_combine_bytes(ftr + 6, csize);
/* master configuration quirks */switch (state->chip->usb_id) {case USB_ID(0x08bb, 0x2702):snd_printk(KERN_INFO"usbmixer: master volume quirk for PCM2702 chip\n");/* disable non-functional volume control */master_bits &= ~(1 << (USB_FEATURE_VOLUME - 1));break;} if (channels > 0) first_ch_bits = snd_usb_combine_bytes(ftr + 6 + csize, csize); else
participants (3)
-
Clemens Ladisch -
Javier Kohen -
Takashi Iwai