Re: [PATCH v2 00/26] Improve DVB documentation and reduce its gap

From	Honza Petrouš <jpetrous@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 00/26] Improve DVB documentation and reduce its gap
Date	2017-09-04 09:20 +0200
Message-ID	<ulTPP-2vA-7@gated-at.bofh.it> (permalink)
References	<ukUbf-5pL-5@gated-at.bofh.it> <ulJnr-4nF-13@gated-at.bofh.it> <ulNU7-6Ya-21@gated-at.bofh.it>
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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

Thread

[PATCH v2 00/26] Improve DVB documentation and reduce its gap Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-09-01 15:30 +0200
  [PATCH v2 11/27] media: fe_property_parameters.rst: better document bandwidth Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-09-01 15:40 +0200
  [PATCH v2 23/27] media: ca-get-slot-info.rst: document this ioctl Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-09-01 15:40 +0200
  [PATCH v2 18/27] media: ca.h: get rid of CA_SET_PID Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-09-01 15:40 +0200
  [PATCH v2 10/27] media: fe_property_parameters.rst: better define properties usage Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-09-01 15:40 +0200
  [PATCH v2 15/27] media: dmx.h: get rid of GET_DMX_EVENT Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-09-01 15:40 +0200
  [PATCH v2 12/27] media: dmx.h: get rid of unused DMX_KERNEL_CLIENT Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-09-01 15:40 +0200
  [PATCH v2 21/27] media: ca-reset.rst: add some description to this ioctl Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-09-01 15:40 +0200
  [PATCH v2 17/27] media: net.rst: Fix the level of a section of the net chapter Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-09-01 15:40 +0200
  [PATCH v2 03/27] media: dvb/intro: use the term Digital TV to refer to the system Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-09-01 15:50 +0200
  [PATCH v2 27/27] media: dst_ca: remove CA_SET_DESCR boilerplate Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-09-01 15:50 +0200
  Re: [PATCH v2 00/26] Improve DVB documentation and reduce its gap Honza Petrouš <jpetrous@gmail.com> - 2017-09-03 22:10 +0200
    Re: [PATCH v2 00/26] Improve DVB documentation and reduce its gap Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-09-04 03:00 +0200
      Re: [PATCH v2 00/26] Improve DVB documentation and reduce its gap Honza Petrouš <jpetrous@gmail.com> - 2017-09-04 09:20 +0200
        Re: [PATCH v2 00/26] Improve DVB documentation and reduce its gap Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-09-04 11:10 +0200
          Re: [PATCH v2 00/26] Improve DVB documentation and reduce its gap Honza Petrouš <jpetrous@gmail.com> - 2017-09-04 11:50 +0200
            Re: [PATCH v2 00/26] Improve DVB documentation and reduce its gap Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-09-04 13:50 +0200
    Re: [PATCH v2 00/26] Improve DVB documentation and reduce its gap Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-09-04 03:20 +0200
  Re: [PATCH v2 00/26] Improve DVB documentation and reduce its gap Honza Petrouš <jpetrous@gmail.com> - 2017-09-03 22:40 +0200

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