Subject: Re: [RFC] alsa integer control ranges

From: Benjamin Herrenschmidt <[email-masked]>
Date: Wed, 17 May 2006 08:00:56 +1000

On Tue, 2006-05-16 at 14:02 +0200, Johannes Berg wrote:
> Apparently all alsa userspace programs including alsamixer suck. Hence,
> this patch is required to make them work properly. Why is it so hard to
> do these additions/subtractions in the program or maybe even in the alsa
> library? The alsa libraries already think they know better and mess up
> all kinds of things.

alsamixer works for me with negative ranges... but all other apps don't
and there are various bugs, I blame apps converted from OSS....

> What are your opinions on this? Should this be required? And if so, why
> do we even have the value.integer.min when we can't use it anyway? 
> 
> The code this patch applies against is in
> http://johannes.sipsolutions.net/snd-aoa.git/ but that isn't all too
> relevant, the patch serves just as an illustration of what is wrong
> here.
> 
> Thanks,
> johannes
> 
> --- snd-aoa.orig/aoa/codecs/onyx/snd-aoa-codec-onyx.c	2006-05-16 12:13:39.663950213 +0200
> +++ snd-aoa/aoa/codecs/onyx/snd-aoa-codec-onyx.c	2006-05-16 12:14:13.698643898 +0200
> @@ -102,8 +102,8 @@ static int onyx_snd_vol_info(struct snd_
>  {
>  	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
>  	uinfo->count = 2;
> -	uinfo->value.integer.min = -128;
> -	uinfo->value.integer.max = -1;
> +	uinfo->value.integer.min = -128+128;
> +	uinfo->value.integer.max = -1+128;
>  	return 0;
>  }
>  
> @@ -115,8 +115,8 @@ static int onyx_snd_vol_get(struct snd_k
>  
>  	onyx_read_register(onyx, ONYX_REG_DAC_ATTEN_LEFT, &l);
>  	onyx_read_register(onyx, ONYX_REG_DAC_ATTEN_RIGHT, &r);
> -	ucontrol->value.integer.value[0] = l;
> -	ucontrol->value.integer.value[1] = r;
> +	ucontrol->value.integer.value[0] = l+128;
> +	ucontrol->value.integer.value[1] = r+128;
>  	return 0;
>  }
>  
> @@ -125,8 +125,8 @@ static int onyx_snd_vol_put(struct snd_k
>  {
>  	struct onyx *onyx = snd_kcontrol_chip(kcontrol);
>  
> -	onyx_write_register(onyx, ONYX_REG_DAC_ATTEN_LEFT, ucontrol->value.integer.value[0]);
> -	onyx_write_register(onyx, ONYX_REG_DAC_ATTEN_RIGHT, ucontrol->value.integer.value[1]);
> +	onyx_write_register(onyx, ONYX_REG_DAC_ATTEN_LEFT, ucontrol->value.integer.value[0]-128);
> +	onyx_write_register(onyx, ONYX_REG_DAC_ATTEN_RIGHT, ucontrol->value.integer.value[1]-128);
>  	/* FIXME: we could be checking if anything changed */
>  	return 1;
>  }
> @@ -145,8 +145,8 @@ static int onyx_snd_inputgain_info(struc
>  {
>  	uinfo->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
>  	uinfo->count = 1;
> -	uinfo->value.integer.min = 3;
> -	uinfo->value.integer.max = 28;
> +	uinfo->value.integer.min = 3-3;
> +	uinfo->value.integer.max = 28-3;
>  	return 0;
>  }
>  
> @@ -157,7 +157,7 @@ static int onyx_snd_inputgain_get(struct
>  	u8 ig;
>  
>  	onyx_read_register(onyx, ONYX_REG_ADC_CONTROL, &ig);
> -	ucontrol->value.integer.value[0] = ig & ONYX_ADC_PGA_GAIN_MASK;
> +	ucontrol->value.integer.value[0] = (ig & ONYX_ADC_PGA_GAIN_MASK)-3;
>  	return 0;
>  }
>  
> @@ -169,7 +169,7 @@ static int onyx_snd_inputgain_put(struct
>  
>  	onyx_read_register(onyx, ONYX_REG_ADC_CONTROL, &val);
>  	val &= ~ONYX_ADC_PGA_GAIN_MASK;
> -	val |= ucontrol->value.integer.value[0] & ONYX_ADC_PGA_GAIN_MASK;
> +	val |= (ucontrol->value.integer.value[0]+3) & ONYX_ADC_PGA_GAIN_MASK;
>  	onyx_write_register(onyx, ONYX_REG_ADC_CONTROL, val);
>  	return 1;
>  }
>