Maris found out that the quirk for TEAC devices to work around the clock setup is needed to apply only when the base clock is changed, e.g. from 48000-based clocks (48000, 96000, 192000, 384000) to 44100-based clocks (44100, 88200, 176400, 352800), or vice versa, while switching to another clock with the same base clock doesn't need the (forcible) interface setup.

This patch implements the optimization for the TEAC clock quirk to avoid the unnecessary interface re-setup.

Fixes: 5ce0b06ae5e6 ("ALSA: usb-audio: Workaround for clock setup on TEAC devices") Reported-by: Maris Abele maris7abele@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/usb/clock.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/sound/usb/clock.c b/sound/usb/clock.c index 3c435d379306..db429320599e 100644 --- a/sound/usb/clock.c +++ b/sound/usb/clock.c @@ -573,10 +573,14 @@ static int set_sample_rate_v2v3(struct snd_usb_audio *chip, }

/* FIXME - TEAC devices require the immediate interface setup */ - if (rate != prev_rate && USB_ID_VENDOR(chip->usb_id) == 0x0644) { - usb_set_interface(chip->dev, fmt->iface, fmt->altsetting); - if (chip->quirk_flags & QUIRK_FLAG_IFACE_DELAY) - msleep(50); + if (USB_ID_VENDOR(chip->usb_id) == 0x0644) { + bool cur_base_48k = (rate % 48000 == 0); + bool prev_base_48k = (prev_rate % 48000 == 0); + if (cur_base_48k != prev_base_48k) { + usb_set_interface(chip->dev, fmt->iface, fmt->altsetting); + if (chip->quirk_flags & QUIRK_FLAG_IFACE_DELAY) + msleep(50); + } }

validation: