ASoC: Don't defer resume work for AC97 codecs

AC97 devices may have other drivers hanging off them directly so need to
have resumed when the resume function returns meaning that we can't defer
the resume - complete it immediately for them. Non-AC97 devices should
not have other drivers hanging directly off the ASoC devices.

We only really need the deferral for non-AC97 devices - it's there since
some I2C buses are very slow and non-AC97 codecs often have large numbers
of registers to restore and require delays to bring the codec up cleanly
leading to a substantial impact on overall resume time.
Reported-by: NRussell King <linux@arm.linux.org.uk>
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

sound/soc/soc-core.c

@@ -767,11 +767,21 @@ static int soc_resume(struct platform_device *pdev)
 {
 	struct snd_soc_device *socdev = platform_get_drvdata(pdev);
 	struct snd_soc_card *card = socdev->card;
+	struct snd_soc_dai *cpu_dai = card->dai_link[0].cpu_dai;
 
-	dev_dbg(socdev->dev, "scheduling resume work\n");
-
-	if (!schedule_work(&card->deferred_resume_work))
-		dev_err(socdev->dev, "resume work item may be lost\n");
+	/* AC97 devices might have other drivers hanging off them so
+	 * need to resume immediately.  Other drivers don't have that
+	 * problem and may take a substantial amount of time to resume
+	 * due to I/O costs and anti-pop so handle them out of line.
+	 */
+	if (cpu_dai->ac97_control) {
+		dev_dbg(socdev->dev, "Resuming AC97 immediately\n");
+		soc_resume_deferred(&card->deferred_resume_work);
+	} else {
+		dev_dbg(socdev->dev, "Scheduling resume work\n");
+		if (!schedule_work(&card->deferred_resume_work))
+			dev_err(socdev->dev, "resume work item may be lost\n");
+	}
 
 	return 0;
 }