Re: [PATCH] ivtv-alsa: Add index to specify device number

[Hans Verkuil <hverkuil@xs4all.nl>]

On 08/13/2015 09:37 PM, Nicolas Sugino wrote:
> When using multiple capture cards, it migth be necessary to identify a specific device with an ALSA one. If not, the order of the ALSA devices might have no relation to the id of the radio or video device.
> 
> Signed-off-by: Nicolas Sugino <nsugino@3way.com.ar>
> ---
>  drivers/media/pci/ivtv/ivtv-alsa-main.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/pci/ivtv/ivtv-alsa-main.c b/drivers/media/pci/ivtv/ivtv-alsa-main.c
> index 41fa215..034908c 100644
> --- a/drivers/media/pci/ivtv/ivtv-alsa-main.c
> +++ b/drivers/media/pci/ivtv/ivtv-alsa-main.c
> @@ -41,6 +41,7 @@
>  #include "ivtv-alsa-pcm.h"
>  
>  int ivtv_alsa_debug;
> +static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX;
>  
>  #define IVTV_DEBUG_ALSA_INFO(fmt, arg...) \
>  	do { \
> @@ -54,6 +55,10 @@ MODULE_PARM_DESC(debug,
>  		 "\t\t\t  1/0x0001: warning\n"
>  		 "\t\t\t  2/0x0002: info\n");
>  
> +module_param_array(index, int, NULL, 0444);
> +MODULE_PARM_DESC(index,
> +		 "Index value for IVTV ALSA capture interface(s).\n");
> +
>  MODULE_AUTHOR("Andy Walls");
>  MODULE_DESCRIPTION("CX23415/CX23416 ALSA Interface");
>  MODULE_SUPPORTED_DEVICE("CX23415/CX23416 MPEG2 encoder");
> @@ -146,7 +151,7 @@ static int snd_ivtv_init(struct v4l2_device *v4l2_dev)
>  
>  	/* (2) Create a card instance */
>  	ret = snd_card_new(&itv->pdev->dev,
> -			   SNDRV_DEFAULT_IDX1, /* use first available id */
> +			   index[itv->instance] == -1 ? SNDRV_DEFAULT_IDX1 : index[itv->instance], /* use first available id if not specified otherwise*/

This line is way too long.

It's more readable if you make an 'idx' local variable that you assign first, then use
in snd_card_new. The comment can go in front of the idx assignment.

>  			   SNDRV_DEFAULT_STR1, /* xid from end of shortname*/
>  			   THIS_MODULE, 0, &sc);
>  	if (ret) {
> @@ -196,6 +201,9 @@ static int snd_ivtv_init(struct v4l2_device *v4l2_dev)
>  		goto err_exit_free;
>  	}
>  
> +	IVTV_ALSA_INFO("%s:: Instance %d registered ALSA card %d\n",
> +			 __func__, itv->instance, index[itv->instance]);

You can't use index[] here since it could give back -1. You can probably
get the actual index from sc.

> +
>  	return 0;
>  
>  err_exit_free:
> 

Regards,

	Hans