lkml.org 
[lkml]   [2010]   [Jun]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] ASoC: Fix overflow bug in SOC_DOUBLE_R_SX_TLV
From
Date
On Fri, 2010-06-18 at 12:56 +1000, Stuart Longland wrote:
> 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>
> ---
> sound/soc/soc-core.c | 4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/sound/soc/soc-core.c b/sound/soc/soc-core.c
> index a82a797..0470288 100644
> --- a/sound/soc/soc-core.c
> +++ b/sound/soc/soc-core.c
> @@ -2400,8 +2400,8 @@ 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);

Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
--
Freelance Developer, SlimLogic Ltd
ASoC and Voltage Regulator Maintainer.
http://www.slimlogic.co.uk



\
 
 \ /
  Last update: 2010-06-18 12:31    [from the cache]
©2003-2011 Jasper Spaans