V4L/DVB (9588): Don't load em28xx audio module for digital-only devices

Rework the logic so that the em28xx-alsa module does not get loaded for devices
that don't support analog audio (such as the em2874)

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

1 files changed, 25 insertions, 4 deletions

diff --git a/drivers/media/video/em28xx/em28xx-video.c b/drivers/media/video/em28xx/em28xx-video.c
index e478ccba0378..129bd06a2ea6 100644
--- a/drivers/media/video/em28xx/em28xx-video.c
+++ b/drivers/media/video/em28xx/em28xx-video.c
@@ -1927,6 +1927,19 @@ static struct video_device *em28xx_vdev_init(struct em28xx *dev,
         return vfd;
 }
 
+int em28xx_supports_audio_extension(struct em28xx *dev)
+{
+        /* The chip dictates whether we support the Empia analog audio
+           extension */
+        switch (dev->chip_id) {
+        case CHIP_ID_EM2874:
+                /* Either a digital-only device or provides AC97 audio */
+                return 0;
+        case CHIP_ID_EM2883:
+        default:
+                return 1;
+        }
+}
 
 static int register_analog_devices(struct em28xx *dev)
 {
@@ -2121,7 +2134,7 @@ static void request_module_async(struct work_struct *work)
 
         if (dev->has_audio_class)
                 request_module("snd-usb-audio");
-        else
+        else if (dev->has_alsa_audio)
                 request_module("em28xx-alsa");
 
         if (dev->has_dvb)
@@ -2230,9 +2243,6 @@ static int em28xx_usb_probe(struct usb_interface *interface,
                 }
         }
 
-        printk(KERN_INFO DRIVER_NAME " %s usb audio class\n",
-                   dev->has_audio_class ? "Has" : "Doesn't have");
-
         /* compute alternate max packet sizes */
         uif = udev->actconfig->interface[0];
 
@@ -2271,6 +2281,17 @@ static int em28xx_usb_probe(struct usb_interface *interface,
 
         em28xx_info("Found %s\n", em28xx_boards[dev->model].name);
 
+        if (dev->has_audio_class == 0) {
+                /* We don't have a USB audio class, let's see if we support
+                   ALSA Audio */
+                dev->has_alsa_audio = em28xx_supports_audio_extension(dev);
+                if (dev->has_alsa_audio)
+                        printk(KERN_INFO DRIVER_NAME " supports alsa audio\n");
+        } else {
+                printk(KERN_INFO DRIVER_NAME " has usb audio class\n");
+        }
+
+
         /* save our data pointer in this interface device */
         usb_set_intfdata(interface, dev);