Commit 40962d7c authored Dec 19, 2009 by Krzysztof Helt Committed by Takashi Iwai Dec 21, 2009

ALSA: fix incorrect rounding direction in snd_interval_ratnum()



The direction of rounding is incorrect in the snd_interval_ratnum()
It was detected with following parameters (sb8 driver playing
8kHz stereo file):
 - num is always 1000000
 - requested frequency rate is from 7999 to 7999 (single frequency)

The first loop calculates div_down(num, freq->min) which is 125.
Thus, a frequency range's minimum value is 1000000 / 125 = 8000 Hz.
The second loop calculates div_up(num, freq->max) which is 126
The frequency range's maximum value is 1000000 / 126 = 7936 Hz.
The range maximum is lower than the range minimum so the function
fails due to empty result range.

Signed-off-by: Krzysztof Helt <krzysztof.h1@wp.pl>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

parent ef86f581

sound/core/pcm_lib.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -758,7 +758,7 @@ int snd_interval_ratnum(struct snd_interval *i,
		int diff;
		if (q == 0)
		q = 1;
		den = div_down(num, q);
		den = div_up(num, q);
		if (den < rats[k].den_min)
		continue;
		if (den > rats[k].den_max)
		@@ -794,7 +794,7 @@ int snd_interval_ratnum(struct snd_interval *i,
		i->empty = 1;
		return -EINVAL;
		}
		den = div_up(num, q);
		den = div_down(num, q);
		if (den > rats[k].den_max)
		continue;
		if (den < rats[k].den_min)