lkml.org 
[lkml]   [2017]   [Sep]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v2 00/26] Improve DVB documentation and reduce its gap
2017-09-04 2:54 GMT+02:00 Mauro Carvalho Chehab <mchehab@s-opensource.com>:
> Em Sun, 3 Sep 2017 22:05:23 +0200
> Honza Petrouš <jpetrous@gmail.com> escreveu:
>
>> 1) #define CA_SET_DESCR _IOW('o', 134, ca_descr_t)
>> ============================================
>>
>> CA_SET_DESCR is used for feeding descrambler device
>> with correct keys (called here "control words") what
>> allows to get services unscrambled.
>>
>> The best docu is:
>>
>> "Digital Video Broadcasting (DVB);
>> Support for use of the DVB Scrambling Algorithm version 3
>> within digital broadcasting systems"
>>
>> Defined as DVB Document A125 and publicly
>> available here:
>>
>> https://www.dvb.org/resources/public/standards/a125_dvb-csa3.pdf
>>
>>
>> typedef struct ca_descr {
>> unsigned int index;
>> unsigned int parity; /* 0 == even, 1 == odd */
>> unsigned char cw[8];
>> } ca_descr_t;
>>
>> The 'index' is adress of the descrambler instance, as there exist
>> limited number of them (retieved by CA_GET_DESCR_INFO).
>
> Thanks for the info. If I understood well, the enclosed patch should
> be documenting it.
>
>
> Thanks,
> Mauro
>
> [PATCH] 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 9c484317d55c..a6c47205ffd8 100644
> --- 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 f66ed53f4dc7..a62ddf0cebcd 100644
> --- 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];
> };
>
>

Yeh, it should be that way.

BTW, the only issue I have in mind is how to link particular
descrambler with the PID
after your removal of the CA_SET_PID. And yes, I know that currently we have
no any user of such ioctl in our driver base :)

/Honza

\
 
 \ /
  Last update: 2017-09-04 09:14    [W:0.071 / U:1.544 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site