[media] tuner.h: rename TUNER_PAD_IF_OUTPUT to TUNER_PAD_OUTPUT

The output of a tuner is not only IF frequencies. They may also
output audio on some of its pins, and may even be a zero-IF tuner,
with outputs a baseband. So, rename the PAD name to make it
clearer and add a proper documentation about that at tuner.h.

No functional changes.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

1 files changed, 18 insertions, 3 deletions

diff --git a/include/media/tuner.h b/include/media/tuner.h
index e5321fda5489..c5994fe865a0 100644
--- a/include/media/tuner.h
+++ b/include/media/tuner.h
@@ -21,11 +21,26 @@
 
 #include <linux/videodev2.h>
 
-/* Tuner PADs */
-/* FIXME: is this the right place for it? */
+/**
+ * enum tuner_pad_index - tuner pad index
+ *
+ * @TUNER_PAD_RF_INPUT:	Radiofrequency (RF) sink pad, usually linked to a
+ *			RF connector entity.
+ * @TUNER_PAD_OUTPUT:	Tuner output pad. This is actually more complex than
+ *			a single pad output, as, in addition to luminance and
+ *			chrominance IF a tuner may have internally an
+ *			audio decoder (like xc3028) or it may produce an audio
+ *			IF that will be used by an audio decoder like msp34xx.
+ *			It may also have an IF-PLL demodulator on it, like
+ *			tuners with tda9887. Yet, currently, we don't need to
+ *			represent all the dirty details, as this is transparent
+ *			for the V4L2 API usage. So, let's represent all kinds
+ *			of different outputs as a single source pad.
+ * @TUNER_NUM_PADS:	Number of pads of the tuner.
+ */
 enum tuner_pad_index {
 	TUNER_PAD_RF_INPUT,
-	TUNER_PAD_IF_OUTPUT,
+	TUNER_PAD_OUTPUT,
 	TUNER_NUM_PADS
 };