[RFC][PATCH v4 4/4] alsa: jack: implement save-and-restore for jack's hw status

[Hui Wang]

Once we enable the sw_inject for a jack_kctl, the hw status change
will be blocked, but the hw status still could be reported to
snd_jack_report() and be saved to hw_status_cache.

After the sw_inject is disabled, we use the last saved hw_status_cache
to restore jack's status.

Signed-off-by: Hui Wang <hui.wang at canonical.com>
---
 include/sound/jack.h | 1 +
 sound/core/jack.c    | 8 ++++++++
 2 files changed, 9 insertions(+)

diff --git a/include/sound/jack.h b/include/sound/jack.h
index 9eb2b5ec1ec4..1181f536557e 100644
--- a/include/sound/jack.h
+++ b/include/sound/jack.h
@@ -67,6 +67,7 @@ struct snd_jack {
 	char name[100];
 	unsigned int key[6];   /* Keep in sync with definitions above */
 #endif /* CONFIG_SND_JACK_INPUT_DEV */
+	int hw_status_cache;
 	void *private_data;
 	void (*private_free)(struct snd_jack *);
 };
diff --git a/sound/core/jack.c b/sound/core/jack.c
index fc49dae887f8..e15db7894b88 100644
--- a/sound/core/jack.c
+++ b/sound/core/jack.c
@@ -194,8 +194,14 @@ static ssize_t sw_inject_enable_write(struct file *file,
 		goto exit;
 	}
 
+	if (jack_kctl->sw_inject_enable == (!!enable))
+		goto exit;
+
 	jack_kctl->sw_inject_enable = !!enable;
 
+	if (!jack_kctl->sw_inject_enable)
+		snd_jack_report(jack_kctl->jack, jack_kctl->jack->hw_status_cache);
+
  exit:
 	kvfree(buf);
 	return ret;
@@ -679,6 +685,8 @@ void snd_jack_report(struct snd_jack *jack, int status)
 	if (!jack)
 		return;
 
+	jack->hw_status_cache = status;
+
 	list_for_each_entry(jack_kctl, &jack->kctl_list, list)
 		if (jack_kctl->sw_inject_enable)
 			mask_bits |= jack_kctl->mask_bits;
-- 
2.25.1