linux-kernel - [PATCH] ALSA: usb-audio: uac1: Invalidate ctl on interrupt

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Message-Id: <20171116163517.5010-1-julian@jusst.de>
Date:   Thu, 16 Nov 2017 17:35:17 +0100
From:   Julian Scheel <julian@...st.de>
To:     Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
        Bhumika Goyal <bhumirks@...il.com>,
        Julian Scheel <julian@...st.de>,
        Stephen Barber <smbarber@...omium.org>,
        Con Kolivas <con@...ivas.org>, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] ALSA: usb-audio: uac1: Invalidate ctl on interrupt

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>
---
 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 91bc8f18791e..1beb5b4d027e 100644
--- a/sound/usb/mixer.c
+++ b/sound/usb/mixer.c
@@ -2330,9 +2330,14 @@ 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,
-- 
2.15.0