Commit 20630c7f authored Jun 18, 2010 by Stuart Longland Committed by Mark Brown Jun 19, 2010

ASoC: Fix overflow bug in SOC_DOUBLE_R_SX_TLV



When SX_TLV widgets are read, if the gain is set to a value below 0dB,
the mixer control is erroniously read as being at maximum volume.

The value read out of the CODEC register is never sign-extended, and
when the minimum value is subtracted (read; added, since the minimum is
negative) the result is a number greater than the maximum allowed value
for the control, and hence it saturates.

Solution: Mask the result so that it "wraps around", emulating
sign-extension.

Signed-off-by: Stuart Longland <redhatter@gentoo.org>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

parent 43793207

sound/soc/soc-core.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -2396,8 +2396,8 @@ int snd_soc_get_volsw_2r_sx(struct snd_kcontrol *kcontrol,
		int val = snd_soc_read(codec, mc->reg) & mask;
		int valr = snd_soc_read(codec, mc->rreg) & mask;

		ucontrol->value.integer.value[0] = ((val & 0xff)-min);
		ucontrol->value.integer.value[1] = ((valr & 0xff)-min);
		ucontrol->value.integer.value[0] = ((val & 0xff)-min) & mask;
		ucontrol->value.integer.value[1] = ((valr & 0xff)-min) & mask;
		return 0;
		}
		EXPORT_SYMBOL_GPL(snd_soc_get_volsw_2r_sx);

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