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

[Anssi Hannula]

08.06.2014 13:03, Takashi Iwai kirjoitti:
> 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.

OK.

I'm a bit afraid about HDMI 2.x, though, with its reported 32 channel
audio support... but I guess we can tackle that when we actually know
how exactly it works and get driver support.


> 
> 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
>>


-- 
Anssi Hannula