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

[poma <pomidorabelisima@gmail.com>]

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?

Cheers,
poma