[RFC 00/xx] ALSA: ALSA: add snd_stream_is_playback/capture()

Hi Iwai-san, Mark

Current many drivers are using below code to know its direction.

if (direction == SNDRV_PCM_STREAM_PLAYBACK)

I think it should be handled by function. But is it acceptable idea ? Because it will be too many patch-set, I want to know it was acceptable idea or not before posting patch-bomb.

I will post main patch, and sample driver patches.

Thank you for your help !!

Best regards --- Kuninori Morimoto