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Commit c9eab129 authored by James Courtier-Dutton's avatar James Courtier-Dutton Committed by Jaroslav Kysela
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[ALSA] ac97: Fix volume control bit size detection for STAC9704. 



AC97 Codec

Signed-off-by: default avatarJames Courtier-Dutton <James@superbug.co.uk>
parent 7c1d549a

sound/pci/ac97/ac97_codec.c

+5 −0
Original line number Diff line number Diff line
@@ -1078,6 +1078,11 @@ static void check_volume_resolution(ac97_t *ac97, int reg, unsigned char *lo_max 
	for (i = 0 ; i < ARRAY_SIZE(cbit); i++) {

		unsigned short val;

		snd_ac97_write(ac97, reg, 0x8080 | cbit[i] | (cbit[i] << 8));

		/* Do the read twice due to buffers on some ac97 codecs.

		 * e.g. The STAC9704 returns exactly what you wrote the the register

		 * if you read it immediately. This causes the detect routine to fail.

		 */

		val = snd_ac97_read(ac97, reg);

		val = snd_ac97_read(ac97, reg);

		if (! *lo_max && (val & 0x7f) == cbit[i])

			*lo_max = max[i];