ALSA: usb-audio: work around KEF X300A firmware bug

When the driver tries to access Function Unit 10, the KEF X300A
speakers' firmware apparently locks up, making even PCM streaming
impossible.  Work around this by ignoring this FU.

Cc: <stable@vger.kernel.org>
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/mixer_maps.c b/sound/usb/mixer_maps.c
index 32af6b741ef5a8aff8581f90b0c5d583d151a6ee..d1d72ff50347a3118c2e90d5452457b8948ad0d6 100644 (file)
--- a/sound/usb/mixer_maps.c
+++ b/sound/usb/mixer_maps.c
@@ -328,6 +328,11 @@ static struct usbmix_name_map gamecom780_map[] = {
        {}
 };
 
+static const struct usbmix_name_map kef_x300a_map[] = {
+       { 10, NULL }, /* firmware locks up (?) when we try to access this FU */
+       { 0 }
+};
+
 /*
  * Control map entries
  */
@@ -419,6 +424,10 @@ static struct usbmix_ctl_map usbmix_ctl_maps[] = {
                .id = USB_ID(0x200c, 0x1018),
                .map = ebox44_map,
        },
+       {
+               .id = USB_ID(0x27ac, 0x1000),
+               .map = kef_x300a_map,
+       },
        { 0 } /* terminator */
 };