media/drivers/bttv-devel.rst

1 .. SPDX-License-Identifier: GPL-2.0
7 -------------------------
15 bttv-cards.c, which holds the information required for each board.
24 example.  The file Documentation/admin-guide/media/bttv-cardlist.rst has a list
48 Below is a do-it-yourself description for you.
50 The bt8xx chips have 32 general purpose pins, and registers to control
51 these pins.  One register is the output enable register
52 (``BT848_GPIO_OUT_EN``), it says which pins are actively driven by the
53 bt848 chip.  Another one is the data register (``BT848_GPIO_DATA``), where
54 you can get/set the status if these pins.  They can be used for input
57 Most grabber board vendors use these pins to control an external chip
59 These pins are also used by some companies to drive remote control
60 receiver chips.  Some boards use the i2c bus instead of the gpio pins
74 gpiomask specifies which pins are used to control the audio mux chip.
76 (``BT848_GPIO_OUT_EN``) will be set as these pins must be driven by the
79 The ``audiomux[]`` array holds the data values for the different inputs
80 (i.e. which pins must be high/low for tuner/mute/...).  This will be
81 written to the data register (``BT848_GPIO_DATA``) to switch the audio
92 You can have a look at the board to see which of the gpio pins are
93 connected at all and then start trial-and-error ...
113 	out =	_out_put bits of the data register (BT848_GPIO_DATA),
115 	in  = 	_in_put bits of the data register,