linux-kernel - [PATCH 4.9 155/191] ALSA: usb-audio: uac1: Invalidate ctl on interrupt

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Date:   Mon, 29 Jun 2020 11:39:31 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Julian Scheel <julian@...st.de>, Takashi Iwai <tiwai@...e.de>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 155/191] ALSA: usb-audio: uac1: Invalidate ctl on interrupt

From: Julian Scheel <julian@...st.de>

[ Upstream commit b2500b584cfd228d67e1e43daf27c8af865b499e ]

When an interrupt occurs, the value of at least one of the belonging
controls should have changed. To make sure they get re-read from device
on the next read, invalidate the cache. This was correctly implemented
for uac2 already, but missing for uac1.

Signed-off-by: Julian Scheel <julian@...st.de>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 sound/usb/mixer.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/sound/usb/mixer.c b/sound/usb/mixer.c
index 024864ce3f761..60423d2572c7d 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -2397,9 +2397,14 @@ void snd_usb_mixer_notify_id(struct usb_mixer_interface *mixer, int unitid)
 {
 	struct usb_mixer_elem_list *list;
 
-	for (list = mixer->id_elems[unitid]; list; list = list->next_id_elem)
+	for (list = mixer->id_elems[unitid]; list; list = list->next_id_elem) {
+		struct usb_mixer_elem_info *info =
+			(struct usb_mixer_elem_info *)list;
+		/* invalidate cache, so the value is read from the device */
+		info->cached = 0;
 		snd_ctl_notify(mixer->chip->card, SNDRV_CTL_EVENT_MASK_VALUE,
 			       &list->kctl->id);
+	}
 }
 
 static void snd_usb_mixer_dump_cval(struct snd_info_buffer *buffer,
-- 
2.25.1