Commit fa92dd77 authored Apr 25, 2013 by David Henningsson Committed by Takashi Iwai Apr 26, 2013

ALSA: usb - Avoid unnecessary sample rate changes on USB 2.0 clock sources



The Scarlett 2i2 seems to take almost 500 ms to set the sample rate,
even if the clock is currently set to that value. This patch speeds
up prepare of the device, by avoiding setting the clock to something
it already is.

Signed-off-by: David Henningsson <david.henningsson@canonical.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

parent 4b417cf0

sound/usb/clock.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -356,6 +356,8 @@ static int set_sample_rate_v2(struct snd_usb_audio *chip, int iface,
		return clock;

		prev_rate = get_sample_rate_v2(chip, iface, fmt->altsetting, clock);
		if (prev_rate == rate)
		return 0;

		cs_desc = snd_usb_find_clock_source(chip->ctrl_intf, clock);
		writeable = uac2_control_is_writeable(cs_desc->bmControls, UAC2_CS_CONTROL_SAM_FREQ - 1);