Re: [alsa-devel] USB Audio Interface / Denon MC7000 and MC8000 controller

On Thu, 06 Feb 2020 23:09:33 +0100, Alexander Tsoy wrote:

В Чт, 06/02/2020 в 11:06 +0100, Tobias пишет:

...

Thank you so much Alexander! I used latest Kernel and patched as you suggested. The Device is working now giving sound on all 4 channels, even though dmesg still shows the error message as you can see here:

uname -a: Linux tobias-V130 5.5.2 #1 SMP Thu Feb 6 09:41:57 CET 2020 x86_64 x86_64 x86_64 GNU/Linux

dmesg: [ 62.918777] usb 1-1.3: new high-speed USB device number 6 using xhci_hcd [ 62.939293] usb 1-1.3: New USB device found, idVendor=15e4, idProduct=8004, bcdDevice=11.10 [ 62.939295] usb 1-1.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3 [ 62.939297] usb 1-1.3: Product: DENON DJ MC7000 [ 62.939298] usb 1-1.3: Manufacturer: DENON DJ [ 62.939299] usb 1-1.3: SerialNumber: 201603 [ 62.942232] usb 1-1.3: clock source 65 is not valid, cannot use [ 62.943998] usb 1-1.3: clock source 65 is not valid, cannot use [ 63.013306] usb 1-1.3: clock source 65 is not valid, cannot use [ 63.028912] usb 1-1.3: clock source 65 is not valid, cannot use [ 63.029675] usb 1-1.3: clock source 65 is not valid, cannot use [ 63.037813] usb 1-1.3: clock source 65 is not valid, cannot use [ 63.063865] usb 1-1.3: clock source 65 is not valid, cannot use

Yes, this is expected.

...

I checked in file /sound/usb/clock.c that within functions

static int __uac_clock_find_source static int __uac3_clock_find_source

there is another check that possibly gives the warning.

Maybe the warning "cannot use" should not be displayed when a Denon Audio device is attached as it is misleading.

Please try the patch below. I've dropped UAC3 support and changed __uac_clock_find_source() and __uac3_clock_find_source() to print errors only in debug mode, as we make the final decision about clock validity in set_sample_rate_v2v3().

Dear Takashi, what do you think about this approach. Is it acceptable?

Yes, the approach looks good to me. Just a few comments:

diff --git a/sound/usb/clock.c b/sound/usb/clock.c index 018b1ecb5404..e978b46efc85 100644 --- a/sound/usb/clock.c +++ b/sound/usb/clock.c @@ -197,6 +197,32 @@ static bool uac_clock_source_is_valid(struct snd_usb_audio *chip, return data ? true : false; }

+/*

• • Assume the clock is valid if clock source supports only one single sample
• • rate, its type is not external and a terminal is connected directly to it
• • (there is no clock selector). This is needed for some Denon DJ controllers,
• • that always reports that clock is invalid.
• */

+static bool uac_clock_source_is_valid_quirk(struct snd_usb_audio *chip,

• 			    struct audioformat *fmt,
  

• 			    int clock)
  

+{

• if (fmt->protocol == UAC_VERSION_2) {

• struct uac_clock_source_descriptor *cs_desc =
  

• 	snd_usb_find_clock_source(chip->ctrl_intf, clock);
  

• if (!cs_desc)
  

• 	return false;
  

• return (fmt->nr_rates == 1 &&
  

• 	(fmt->clock & 0xff) == cs_desc->bClockID &&
  

• 	(cs_desc->bmAttributes & 0x3) !=
  

• 		UAC_CLOCK_SOURCE_TYPE_EXT);
  

• }
• return false;

IMO it's safer to call from the specific failure path, i.e.

static bool uac_clock_source_is_valid(....) { .... err = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC2_CS_CUR, USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_IN, UAC2_CS_CONTROL_CLOCK_VALID << 8, snd_usb_ctrl_intf(chip) | (source_id << 8), &data, sizeof(data));

if (err < 0) {

if (uac_clock_source_is_valid_quirk(....)) return true;

dev_warn(&dev->dev, "%s(): cannot get clock validity for id %d\n", __func__, source_id); return false; }

Then you can pass cs_desc there, too.

+}

static int __uac_clock_find_source(struct snd_usb_audio *chip, int entity_id, unsigned long *visited, bool validate) { @@ -219,7 +245,7 @@ static int __uac_clock_find_source(struct snd_usb_audio *chip, int entity_id, entity_id = source->bClockID; if (validate && !uac_clock_source_is_valid(chip, UAC_VERSION_2, entity_id)) {

• 	usb_audio_err(chip,
  

• 	usb_audio_dbg(chip,
  	"clock source %d is not valid, cannot use\n",
  	entity_id);
  return -ENXIO;
  

Hm, it's not good to hide the error message always. This is a common error on many devices and suppressing it would look cleaner but also hide what's the reason. Maybe we can add nowarn bool flag for certain code paths?

thanks,

Takashi