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media: docs: cleanup bttv-devel.rst file

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This file was converted from text at the early ReST days.
We learnt a lot about how to produce a nicer result while
keeping the file better readable as plain text.

Change some ReST markups to make it look better, both at
the output formats and as plain text file.

While here, remove references for the old bt848/winutil
tool, as it seems that it doesn't exist anymore.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
This commit is contained in:
Mauro Carvalho Chehab 2020-03-10 16:01:08 +01:00
parent 371f6ff57f
commit 4605a6102a
1 changed files with 23 additions and 30 deletions
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53
Documentation/driver-api/media/drivers/bttv-devel.rst
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@ -15,15 +15,15 @@ To handle the grabber boards correctly, there is a array tvcards[] in
bttv-cards.c, which holds the information required for each board.
Sound will work only, if the correct entry is used (for video it often
makes no difference). The bttv driver prints a line to the kernel
log, telling which card type is used. Like this one:
.. code-block:: none
log, telling which card type is used. Like this one::
bttv0: model: BT848(Hauppauge old) [autodetected]
You should verify this is correct. If it isn't, you have to pass the
correct board type as insmod argument, "insmod bttv card=2" for
example. The file CARDLIST has a list of valid arguments for card.
correct board type as insmod argument, ``insmod bttv card=2`` for
example. The file :doc:`/admin-guide/media/bttv-cardlist` has a list
of valid arguments for card.
If your card isn't listed there, you might check the source code for
new entries which are not listed yet. If there isn't one for your
card, you can check if one of the existing entries does work for you
@ -32,7 +32,7 @@ card, you can check if one of the existing entries does work for you
Some boards have an extra processor for sound to do stereo decoding
and other nice features. The msp34xx chips are used by Hauppauge for
example. If your board has one, you might have to load a helper
module like msp3400.o to make sound work. If there isn't one for the
module like ``msp3400`` to make sound work. If there isn't one for the
chip used on your board: Bad luck. Start writing a new one. Well,
you might want to check the video4linux mailing list archive first...
@ -49,8 +49,8 @@ Below is a do-it-yourself description for you.
The bt8xx chips have 32 general purpose pins, and registers to control
these pins. One register is the output enable register
(BT848_GPIO_OUT_EN), it says which pins are actively driven by the
bt848 chip. Another one is the data register (BT848_GPIO_DATA), where
(``BT848_GPIO_OUT_EN``), it says which pins are actively driven by the
bt848 chip. Another one is the data register (``BT848_GPIO_DATA``), where
you can get/set the status if these pins. They can be used for input
and output.
@ -62,25 +62,23 @@ to connect the mux chip.
As mentioned above, there is a array which holds the required
information for each known board. You basically have to create a new
line for your board. The important fields are these two:
line for your board. The important fields are these two::
.. code-block:: c
struct tvcard
{
[ ... ]
u32 gpiomask;
u32 audiomux[6]; /* Tuner, Radio, external, internal, mute, stereo */
};
struct tvcard
{
[ ... ]
u32 gpiomask;
u32 audiomux[6]; /* Tuner, Radio, external, internal, mute, stereo */
};
gpiomask specifies which pins are used to control the audio mux chip.
The corresponding bits in the output enable register
(BT848_GPIO_OUT_EN) will be set as these pins must be driven by the
(``BT848_GPIO_OUT_EN``) will be set as these pins must be driven by the
bt848 chip.
The audiomux\[\] array holds the data values for the different inputs
The ``audiomux[]`` array holds the data values for the different inputs
(i.e. which pins must be high/low for tuner/mute/...). This will be
written to the data register (BT848_GPIO_DATA) to switch the audio
written to the data register (``BT848_GPIO_DATA``) to switch the audio
mux.
@ -88,12 +86,9 @@ What you have to do is figure out the correct values for gpiomask and
the audiomux array. If you have Windows and the drivers four your
card installed, you might to check out if you can read these registers
values used by the windows driver. A tool to do this is available
from ftp://telepresence.dmem.strath.ac.uk/pub/bt848/winutil, but it
doesn't work with bt878 boards according to some reports I received.
Another one with bt878 support is available from
http://btwincap.sourceforge.net/Files/btspy2.00.zip
from http://btwincap.sourceforge.net/download.html.
You might also dig around in the \*.ini files of the Windows applications.
You might also dig around in the ``*.ini`` files of the Windows applications.
You can have a look at the board to see which of the gpio pins are
connected at all and then start trial-and-error ...
@ -101,18 +96,16 @@ connected at all and then start trial-and-error ...
Starting with release 0.7.41 bttv has a number of insmod options to
make the gpio debugging easier:
.. code-block:: none
================= ==============================================
bttv_gpio=0/1 enable/disable gpio debug messages
gpiomask=n set the gpiomask value
audiomux=i,j,... set the values of the audiomux array
audioall=a set the values of the audiomux array (one
value for all array elements, useful to check
out which effect the particular value has).
================= ==============================================
The messages printed with bttv_gpio=1 look like this:
.. code-block:: none
The messages printed with ``bttv_gpio=1`` look like this::
bttv0: gpio: en=00000027, out=00000024 in=00ffffd8 [audio: off]