V4L/DVB (6952): Add code for autoloading em28xx-alsa, if needed

Older em28xx devices does implement standard Audio Class.

However, on newer devices, this were replaced by a Vendor Class. This
patch autodetects that an em28xx lacks Audio Class and auto-loads
em28xx-alsa, for the devices that implements only a Vendor Class.

For devices with Audio Class, snd-usb-audio module will provide an ALSA
interface.

This patch uses the request_module_async function as defined on cx88-mpeg.c, 
originally wrote by Markus Rechberger.

Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/media/video/em28xx/em28xx.h b/drivers/media/video/em28xx/em28xx.h
index c2d9ae0ac618..9eb213132da1 100644
--- a/drivers/media/video/em28xx/em28xx.h
+++ b/drivers/media/video/em28xx/em28xx.h
@@ -246,6 +246,7 @@ struct em28xx {
         unsigned int has_msp34xx:1;
         unsigned int has_tda9887:1;
         unsigned int stream_on:1;       /* Locks streams */
+        unsigned int has_audio_class:1;
 
         int video_inputs;       /* number of video inputs */
         struct list_head        devlist;
@@ -295,6 +296,8 @@ struct em28xx {
         enum em28xx_stream_state stream;
         enum em28xx_io_method io;
 
+        struct work_struct         request_module_wk;
+
         /* locks */
         struct mutex lock;
         spinlock_t queue_lock;