Re: [PATCH v3 3/4] stk1160: Add module param for setting the record gain.

[Mauro Carvalho Chehab <mchehab@s-opensource.com>]

Em Sun, 27 Nov 2016 12:11:48 +0100
Marcel Hasler <mahasler@gmail.com> escreveu:

> Allow setting a custom record gain for the internal AC97 codec (if available). This can be
> a value between 0 and 15, 8 is the default and should be suitable for most users. The Windows
> driver also sets this to 8 without any possibility for changing it.

The problem of removing the mixer is that you need this kind of
crap to setup the volumes on a non-standard way.

NACK.

Instead, keep the alsa mixer. The way other drivers do (for example, 
em28xx) is that they configure the mixer when an input is selected,
increasing the volume of the active audio channel to 100% and muting
the other audio channels. Yet, as the alsa mixer is exported, users 
can change the mixer settings in runtime using some alsa (or pa)
mixer application.

> 
> Signed-off-by: Marcel Hasler <mahasler@gmail.com>
> ---
>  drivers/media/usb/stk1160/stk1160-ac97.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/usb/stk1160/stk1160-ac97.c b/drivers/media/usb/stk1160/stk1160-ac97.c
> index 95648ac..60327af 100644
> --- a/drivers/media/usb/stk1160/stk1160-ac97.c
> +++ b/drivers/media/usb/stk1160/stk1160-ac97.c
> @@ -28,6 +28,11 @@
>  #include "stk1160.h"
>  #include "stk1160-reg.h"
>  
> +static u8 gain = 8;
> +
> +module_param(gain, byte, 0444);
> +MODULE_PARM_DESC(gain, "Set capture gain level if AC97 codec is available (0-15, default: 8)");
> +
>  static void stk1160_write_ac97(struct stk1160 *dev, u16 reg, u16 value)
>  {
>  	/* Set codec register address */
> @@ -136,7 +141,10 @@ void stk1160_ac97_setup(struct stk1160 *dev)
>  	stk1160_write_ac97(dev, 0x16, 0x0808); /* Aux volume */
>  	stk1160_write_ac97(dev, 0x1a, 0x0404); /* Record select */
>  	stk1160_write_ac97(dev, 0x02, 0x0000); /* Master volume */
> -	stk1160_write_ac97(dev, 0x1c, 0x0808); /* Record gain */
> +
> +	/* Record gain */
> +	gain = (gain > 15) ? 15 : gain;
> +	stk1160_write_ac97(dev, 0x1c, (gain<<8) | gain);
>  
>  #ifdef DEBUG
>  	stk1160_ac97_dump_regs(dev);



Thanks,
Mauro