ALSA: pcm: Handle XRUN at trigger START

When the driver returns -EPIPE for indicating an XRUN already at PCM
trigger START, we should treat properly and set it to the XRUN state.
Otherwise the state is missing and the application would try to issue
trigger again without knowing that it's in an error state.

This is just for a theoretical bug, and it won't happen in most
cases.

Link: https://lore.kernel.org/r/[email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Takashi Iwai <[email protected]>

Author: tiwai

sound/core/pcm_native.c

@@ -1424,9 +1424,15 @@ static int snd_pcm_pre_start(struct snd_pcm_substream *substream,
 static int snd_pcm_do_start(struct snd_pcm_substream *substream,
 			    snd_pcm_state_t state)
 {
+	int err;
+
 	if (substream->runtime->trigger_master != substream)
 		return 0;
-	return substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_START);
+	err = substream->ops->trigger(substream, SNDRV_PCM_TRIGGER_START);
+	/* XRUN happened during the start */
+	if (err == -EPIPE)
+		__snd_pcm_set_state(substream->runtime, SNDRV_PCM_STATE_XRUN);
+	return err;
 }
 
 static void snd_pcm_undo_start(struct snd_pcm_substream *substream,