[media] em28xx: check if a device has audio earlier"

GIT_AUTHOR_DATE=1409603039
This reverts

commit b99f0aadd33fad269c8e62b5bec8b5c012a44a56
Author: Mauro Carvalho Chehab <m.chehab@samsung.com>

    [media] em28xx: check if a device has audio earlier

    Better to split chipset detection from the audio setup. So, move the
    detection code to em28xx_init_dev().

It broke analog audio of the Hauppauge winTV HVR 900 and very likely many other
em28xx devices.

Background:
The local variable has_audio in em28xx_usb_probe() describes if the currently
probed _usb_interface_ has an audio endpoint, while dev->audio_mode.has_audio
means that the _device_ as a whole provides analog audio.
Hence it is wrong to set dev->audio_mode.has_audio = has_audio in em28xx_usb_probe().
As result, audio support is no longer detected and configured on devices which
have the audio endpoint on a separate interface, because em28xx_audio_setup()
bails out immediately at the beginning.

Revert the faulty commit to restore the old audio detection procedure, which checks
the chip configuration register to determine if the device has analog audio.

Cc: <stable@vger.kernel.org>	# 3.14 to 3.16
Reported-by: Oravecz Csaba <oravecz@nytud.mta.hu>
Tested-by: Oravecz Csaba <oravecz@nytud.mta.hu>
Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/media/usb/em28xx/em28xx-cards.c

@@ -3098,16 +3098,6 @@ static int em28xx_init_dev(struct em28xx *dev, struct usb_device *udev,
 		}
 	}
 
-	if (dev->chip_id == CHIP_ID_EM2870 ||
-	    dev->chip_id == CHIP_ID_EM2874 ||
-	    dev->chip_id == CHIP_ID_EM28174 ||
-	    dev->chip_id == CHIP_ID_EM28178) {
-		/* Digital only device - don't load any alsa module */
-		dev->audio_mode.has_audio = false;
-		dev->has_audio_class = false;
-		dev->has_alsa_audio = false;
-	}
-
 	if (chip_name != default_chip_name)
 		printk(KERN_INFO DRIVER_NAME
 		       ": chip ID is %s\n", chip_name);
@@ -3377,7 +3367,6 @@ static int em28xx_usb_probe(struct usb_interface *interface,
 	dev->alt   = -1;
 	dev->is_audio_only = has_audio && !(has_video || has_dvb);
 	dev->has_alsa_audio = has_audio;
-	dev->audio_mode.has_audio = has_audio;
 	dev->has_video = has_video;
 	dev->ifnum = ifnum;
 

drivers/media/usb/em28xx/em28xx-core.c

@@ -506,8 +506,18 @@ int em28xx_audio_setup(struct em28xx *dev)
 	int vid1, vid2, feat, cfg;
 	u32 vid;
 
-	if (!dev->audio_mode.has_audio)
+	if (dev->chip_id == CHIP_ID_EM2870 ||
+	    dev->chip_id == CHIP_ID_EM2874 ||
+	    dev->chip_id == CHIP_ID_EM28174 ||
+	    dev->chip_id == CHIP_ID_EM28178) {
+		/* Digital only device - don't load any alsa module */
+		dev->audio_mode.has_audio = false;
+		dev->has_audio_class = false;
+		dev->has_alsa_audio = false;
 		return 0;
+	}
+
+	dev->audio_mode.has_audio = true;
 
 	/* See how this device is configured */
 	cfg = em28xx_read_reg(dev, EM28XX_R00_CHIPCFG);