Extern or forward variable declaration at include/sound/soc-dapm.h, line 379 References: drivers/staging/greybus/audio_helper.c, line 94 include/sound/soc-dapm.h, line 379 include/sound/soc-dapm.h, line 504 include/sound/soc-dapm.h, line 762 sound/soc/soc-dapm.c, line 205 sound/soc/soc-dapm.c, line 207 sound/soc/soc-dapm.c, line 1018 sound/soc/soc-dapm.c, line 1159 sound/soc/soc-dapm.c, line 1161 sound/soc/soc-dapm.c, line 1189 sound/soc/soc-dapm.c, line 1192 sound/soc/soc-dapm.c, line 1194 sound/soc/soc-dapm.c, line 1196 sound/soc/soc-dapm.c, line 1254 sound/soc/soc-dapm.c, line 1272 sound/soc/soc-dapm.c, line 1300 sound/soc/soc-dapm.c, line 2105 sound/soc/soc-dapm.c, line 2488 sound/soc/soc-dapm.c, line 2714 sound/soc/soc-dapm.c, line 2814 sound/soc/soc-dapm.c, line 3604 sound/soc/soc-pcm.c, line 1266