media: ca docs: document CA_SET_DESCR ioctl and structs

The av7110 driver uses CA_SET_DESCR to store the descrambler
control words at the CA descrambler slots.

Document it.

Thanks-to: Honza Petrouš <jpetrous@gmail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

diff --git a/Documentation/media/uapi/dvb/ca-set-descr.rst b/Documentation/media/uapi/dvb/ca-set-descr.rst
index 9c48431..a6c4720 100644 (file)
--- a/Documentation/media/uapi/dvb/ca-set-descr.rst
+++ b/Documentation/media/uapi/dvb/ca-set-descr.rst
@@ -28,22 +28,11 @@ Arguments
 ``msg``
   Pointer to struct :c:type:`ca_descr`.
 
-.. c:type:: ca_descr
-
-.. code-block:: c
-
-    struct ca_descr {
-       unsigned int index;
-       unsigned int parity;
-       unsigned char cw[8];
-    };
-
-
 Description
 -----------
 
-.. note:: This ioctl is undocumented. Documentation is welcome.
-
+CA_SET_DESCR is used for feeding descrambler CA slots with descrambling
+keys (refered as control words).
 
 Return Value
 ------------

diff --git a/include/uapi/linux/dvb/ca.h b/include/uapi/linux/dvb/ca.h
index 7ee641b..c36fdb8 100644 (file)
--- a/include/uapi/linux/dvb/ca.h
+++ b/include/uapi/linux/dvb/ca.h
@@ -109,9 +109,16 @@ struct ca_msg {
        unsigned char msg[256];
 };
 
+/**
+ * struct ca_descr - CA descrambler control words info
+ *
+ * @index: CA Descrambler slot
+ * @parity: control words parity, where 0 means even and 1 means odd
+ * @cw: CA Descrambler control words
+ */
 struct ca_descr {
        unsigned int index;
-       unsigned int parity;    /* 0 == even, 1 == odd */
+       unsigned int parity;
        unsigned char cw[8];
 };