Re: GPIO interface between DVB sub-drivers (bridge, demod, tuner)

[Antti Palosaari <crope@iki.fi>]

On 07/30/2012 12:21 AM, poma wrote:
> On 07/20/2012 03:43 AM, Antti Palosaari wrote:
>> On 07/13/2012 12:07 AM, Steven Toth wrote:
>>> On Thu, Jul 12, 2012 at 4:49 PM, Steven Toth <stoth@kernellabs.com>
>>> wrote:
>>>> Nobody understands the relationship between the bridge and the
>>>> sub-component as well as the bridge driver. The current interfaces are
>>>> limiting in many ways. We solve that today with rather ugly 'attach'
>>>> structures that are inflexible, for example to set gpios to a default
>>>> state.
>>>> Then, once that interface is attached, the bridge effectively loses
>>>> most of
>>>> the control to the tuner and/or demod. The result is a large disconnect
>>>> between the bridge and subcomponents.
>>>>
>>>> Why limit any interface extension to GPIOs? Why not make something a
>>>> little more flexible so we can pass custom messages around?
>>
>>>> What did you ever decide about the enable/disable of the LNA? And, how
>>>> would the bridge do that in your proposed solution? Via the proposed
>>>> GPIO
>>>> interface?
>>
>> GPIO / LNA is ready, see following patches:
>> add LNA support for DVB API
>> cxd2820r: use Kernel GPIO for GPIO access
>> em28xx: implement FE set_lna() callback
>>
>> from:
>> http://git.linuxtv.org/anttip/media_tree.git/shortlog/refs/heads/dvb_core
>>
>> Kernel GPIOs were quite easy to implement and use - when needed
>> knowledge was gathered after all the testing and study. I wonder why
>> none was done that earlier for DVB...
>>
>> It also offer nice debug/devel feature as you can mount those GPIOs via
>> sysfs and use directly.
>>
>
> Above mentioned GPIO functionality must be implemented in driver itself
> to use /sys/class/gpio/… sysfs interface, right?
> It is not enough to build kernel with CONFIG_GENERIC_GPIO=y,
> CONFIG_GPIOLIB=y, CONFIG_GPIO_SYSFS, right?

You will need to implement callbacks for gpiolib. sysfs interface is 
then get for free.

regards
Antti

-- 
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