[alsa-devel] [PATCH] pcm: Fix channel map query when there are lots of maps

[Takashi Iwai]

At Sun,  8 Jun 2014 12:58:56 +0300,
Anssi Hannula wrote:
> 
> On most HDA Intel HDMI devices, the channel map list is approx. 500 ints
> in size, making the 256-sized buffer used by
> snd_pcm_query_chmaps_from_hw() too small and causing the query to fail
> (NULL result to caller, ENOMEM).
> 
> Bump the buffer size to 2048 ints.
> 
> Signed-off-by: Anssi Hannula <anssi.hannula at iki.fi>
> ---
> 
> Found while writing XBMC support.
> 
> I don't like just bumping the buffer size, so I hope you have some idea
> of a better solution?
> I guess one way would be just to retry with a dynamically allocated
> bigger buffer on ENOMEM, if there is nothing better...

For user-space, this stack size doesn't matter too much, I suppose.
Unless we'll hit really too big size, I guess we can keep in this
way.  So, I applied it as is.


thanks,

Takashi


> 
>  src/pcm/pcm_hw.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/pcm/pcm_hw.c b/src/pcm/pcm_hw.c
> index 9ff83a9..ed83197 100644
> --- a/src/pcm/pcm_hw.c
> +++ b/src/pcm/pcm_hw.c
> @@ -1051,7 +1051,7 @@ snd_pcm_query_chmaps_from_hw(int card, int dev, int subdev,
>  {
>  	snd_ctl_t *ctl;
>  	snd_ctl_elem_id_t *id;
> -	unsigned int tlv[256], *start;
> +	unsigned int tlv[2048], *start;
>  	snd_pcm_chmap_query_t **map;
>  	int i, ret, nums;
>  
> -- 
> 1.8.4.5
>