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| author | Jörg Krause <joerg.krause@embedded.rocks> | 2016-05-08 20:48:42 +0200 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2016-05-09 14:52:04 +0200 |
| commit | 85bf9915989e0a338632739684c75192c1753239 (patch) | |
| tree | 8900a4c34e4bd70edc1d99ff83f732d66f86cf1e | |
| parent | 76af5bf833323d8ae1caa23d592a959e74990932 (diff) | |
| download | alsa-lib-85bf9915989e0a338632739684c75192c1753239.tar.gz | |
pcm: softvol: fix conversion of TLVs min_db and max_dB value
Both, min_dB and max_dB, are floating type whereas the TLV is (always)
unsigned.
The problem with the conversion of a negative floating-point number into an
unsigned integer is, that the behavior is undefined. This may, depending on
the platform, result in a wrong TLV, i.e. for the default values of min_dB
(-51dB) and max_dB (0dB), alsactl generates the following state on an ARM
cpu build with GCC:
control.1 {
iface MIXER
name Master
value.0 255
value.1 255
comment {
access 'read write user'
type INTEGER
count 2
range '0 - 255'
tlv '00000001000000080000000000000014'
dbmin 0
dbmax 5100
dbvalue.0 5100
dbvalue.1 5100
}
}
With the fix applied, alsactl stores the correct TLV:
control.1 {
iface MIXER
name Master
value.0 255
value.1 255
comment {
access 'read write user'
type INTEGER
count 2
range '0 - 255'
tlv '0000000100000008ffffec1400000014'
dbmin -5100
dbmax 0
dbvalue.0 0
dbvalue.1 0
}
}
Also tested for different combinations of min_dB and max_dB other than the
default values.
Replaces:
http://mailman.alsa-project.org/pipermail/alsa-devel/2016-May/107733.html
Fixes:
http://mailman.alsa-project.org/pipermail/alsa-devel/2016-May/107628.html
Cc: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
| -rw-r--r-- | src/pcm/pcm_softvol.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/src/pcm/pcm_softvol.c b/src/pcm/pcm_softvol.c index 802aa4b7..5492db8c 100644 --- a/src/pcm/pcm_softvol.c +++ b/src/pcm/pcm_softvol.c @@ -658,8 +658,8 @@ static int add_tlv_info(snd_pcm_softvol_t *svol, snd_ctl_elem_info_t *cinfo) unsigned int tlv[4]; tlv[0] = SND_CTL_TLVT_DB_SCALE; tlv[1] = 2 * sizeof(int); - tlv[2] = svol->min_dB * 100; - tlv[3] = (svol->max_dB - svol->min_dB) * 100 / svol->max_val; + tlv[2] = (int)(svol->min_dB * 100); + tlv[3] = (int)((svol->max_dB - svol->min_dB) * 100 / svol->max_val); return snd_ctl_elem_tlv_write(svol->ctl, &cinfo->id, tlv); } |