V4L/DVB (8017): Ensure em28xx extensions only get run against devs that support them

em28xx-audio.c
em28xx-dvb.c
 - Em28xx extensions should ensure they are being only loaded against devices
   that support them.  Deals with case where there are multiple em28xx
   devices, some of which have DVB (or ALSA) support and some do not.

Signed-off-by: Devin Heitmueller <devin.heitmueller@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

2 files changed, 22 insertions, 0 deletions

diff --git a/drivers/media/video/em28xx/em28xx-audio.c b/drivers/media/video/em28xx/em28xx-audio.c
index 92b2a6db4fdc..343dff0f8a04 100644
--- a/drivers/media/video/em28xx/em28xx-audio.c
+++ b/drivers/media/video/em28xx/em28xx-audio.c
@@ -415,6 +415,12 @@ static int em28xx_audio_init(struct em28xx *dev)
         static int          devnr;
         int                 ret, err;
 
+        if (dev->has_audio_class) {
+                /* This device does not support the extension (in this case
+                   the device is expecting the snd-usb-audio module */
+                return 0;
+        }
+
         printk(KERN_INFO "em28xx-audio.c: probing for em28x1 "
                          "non standard usbaudio\n");
         printk(KERN_INFO "em28xx-audio.c: Copyright (C) 2006 Markus "
@@ -458,6 +464,12 @@ static int em28xx_audio_fini(struct em28xx *dev)
         if (dev == NULL)
                 return 0;
 
+        if (dev->has_audio_class) {
+                /* This device does not support the extension (in this case
+                   the device is expecting the snd-usb-audio module */
+                return 0;
+        }
+
         if (dev->adev) {
                 snd_card_free(dev->adev->sndcard);
                 kfree(dev->adev);
diff --git a/drivers/media/video/em28xx/em28xx-dvb.c b/drivers/media/video/em28xx/em28xx-dvb.c
index 8cf4983f0039..0b2333ee07f8 100644
--- a/drivers/media/video/em28xx/em28xx-dvb.c
+++ b/drivers/media/video/em28xx/em28xx-dvb.c
@@ -382,6 +382,11 @@ static int dvb_init(struct em28xx *dev)
         int result = 0;
         struct em28xx_dvb *dvb;
 
+        if (!dev->has_dvb) {
+                /* This device does not support the extension */
+                return 0;
+        }
+
         dvb = kzalloc(sizeof(struct em28xx_dvb), GFP_KERNEL);
 
         if (dvb == NULL) {
@@ -444,6 +449,11 @@ out_free:
 
 static int dvb_fini(struct em28xx *dev)
 {
+        if (!dev->has_dvb) {
+                /* This device does not support the extension */
+                return 0;
+        }
+
         if (dev->dvb) {
                 unregister_dvb(dev->dvb);
                 dev->dvb = NULL;