V4L/DVB (11979): em28xx: don't create audio device if not supported

In cases where the device does not actually provide a USB audio class *or*
vendor audio, do not load the driver that provides vendor audio support (such
as the KWorld 2800d).  Otherwise, the /dev/audio1 device file gets created and
users get confused.

Also, reworks the logic a bit so that we don't try to inspect the register
content if the register read failed entirely.

Signed-off-by: Devin Heitmueller <dheitmueller@kernellabs.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 12 insertions, 9 deletions

diff --git a/drivers/media/video/em28xx/em28xx-core.c b/drivers/media/video/em28xx/em28xx-core.c
index b7a2fedc3904..c8d7ce8fbd36 100644
--- a/drivers/media/video/em28xx/em28xx-core.c
+++ b/drivers/media/video/em28xx/em28xx-core.c
@@ -500,18 +500,21 @@ int em28xx_audio_setup(struct em28xx *dev)
 
         /* See how this device is configured */
         cfg = em28xx_read_reg(dev, EM28XX_R00_CHIPCFG);
-        if (cfg < 0)
+        em28xx_info("Config register raw data: 0x%02x\n", cfg);
+        if (cfg < 0) {
+                /* Register read error?  */
                 cfg = EM28XX_CHIPCFG_AC97; /* Be conservative */
-        else
-                em28xx_info("Config register raw data: 0x%02x\n", cfg);
-
-        if ((cfg & EM28XX_CHIPCFG_AUDIOMASK) ==
-                    EM28XX_CHIPCFG_I2S_3_SAMPRATES) {
+        } else if ((cfg & EM28XX_CHIPCFG_AUDIOMASK) == 0x00) {
+                /* The device doesn't have vendor audio at all */
+                dev->has_alsa_audio = 0;
+                dev->audio_mode.has_audio = 0;
+                return 0;
+        } else if ((cfg & EM28XX_CHIPCFG_AUDIOMASK) ==
+                   EM28XX_CHIPCFG_I2S_3_SAMPRATES) {
                 em28xx_info("I2S Audio (3 sample rates)\n");
                 dev->audio_mode.i2s_3rates = 1;
-        }
-        if ((cfg & EM28XX_CHIPCFG_AUDIOMASK) ==
-                    EM28XX_CHIPCFG_I2S_5_SAMPRATES) {
+        } else if ((cfg & EM28XX_CHIPCFG_AUDIOMASK) ==
+                   EM28XX_CHIPCFG_I2S_5_SAMPRATES) {
                 em28xx_info("I2S Audio (5 sample rates)\n");
                 dev->audio_mode.i2s_5rates = 1;
         }