On 21/08/2019 18:05, Takashi Iwai wrote:
On Wed, 21 Aug 2019 12:02:25 +0200, Srinivas Kandagatla wrote:
From: Deepa Madiregama dmadireg@codeaurora.org
- mixer_ctl_set() function is limiting the volume level to particular range. This results in incorrect initial volume setting for that device.
- In USB mixer while calculating the dBmin/dBmax values resolution factor is hardcoded to 256 which results in populating the wrong values for dBmin/dBmax.
- Fix is to use appropriate resolution factor while calculating the dBmin/dBmax values.
This change doesn't sound right. Basically the values returned from USB-audio FEATURE UNIT or MIXER UNIT are always in 1/256 dB unit, per definition. And we pass dB min/max to user-space as TLV_DB_MINMAX(), i.e. TLV points just both min and max, no matter what scale is. I believe that the current code is correct in this regard.
So, it's either a firmware bug that gives the wrong values back, or the case we still don't cover, e.g. multiple RANGE values for UAC2/UAC3.
Please check what exactly doesn't work as expected. Which value is returned from the USB-audio device and what is wrongly interpreted.
Thanks for the detailed review.
I see https://www.usb.org/sites/default/files/audio10.pdf clearly specifies Mixer unit is always 1/256dB units.
This patch has been carried in Qcom downstream kernels for past many years to fix very low Initial volume setting on some USB headsets like Logitech S-150 USB Speakers and Nokia HS-82 USB headset.
Its highly likely that its a firmware bug!, but I will try to get it retested on latest kernel and collect some logs!
Thanks, srini
thanks,
Takashi
Signed-off-by: Deepa Madiregama dmadireg@codeaurora.org Signed-off-by: Banajit Goswami bgoswami@codeaurora.org Signed-off-by: Meng Wang mwang@codeaurora.org Signed-off-by: Srinivas Kandagatla srinivas.kandagatla@linaro.org
sound/usb/mixer.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c index 5070a6a76ab3..a67448327d07 100644 --- a/sound/usb/mixer.c +++ b/sound/usb/mixer.c @@ -1248,8 +1248,10 @@ static int get_min_max_with_quirks(struct usb_mixer_elem_info *cval, /* USB descriptions contain the dB scale in 1/256 dB unit * while ALSA TLV contains in 1/100 dB unit */
- cval->dBmin = (convert_signed_value(cval, cval->min) * 100) / 256;
- cval->dBmax = (convert_signed_value(cval, cval->max) * 100) / 256;
- cval->dBmin =
(convert_signed_value(cval, cval->min) * 100) / (cval->res);- cval->dBmax =
(convert_signed_value(cval, cval->max) * 100) / (cval->res);-- 2.21.0