Re: [PATCH v4] Input: synaptics-rmi4: Add F30 support

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Andrew,

On Fri, Aug 07, 2015 at 05:36:51PM -0700, Andrew Duggan wrote:
> Hi Dmitry,
> 
> With the renewed interest in supporting SMBus with the Synaptics
> RMI4 driver I thought I would look into this again. I'm sorry for
> not responding to your comments sooner, especially since you took
> the time to read the F30 spec. Now that it has been over a year
> later we may need to essentially start over. But, this time I will
> make sure to follow up and hopefully not waste your time in the
> future.

This is great and I agree that we need to get RMI4 into kernel proper.
Unfortunately it is quite large body of code and I am afraid that I wont
be able to give it enough attention until mid-September.

In the meantime, Benjamin, maybe you could work with Andrew? You have
done a lot of work on input side.

Thanks.

> 
> On 07/27/2014 12:26 AM, Dmitry Torokhov wrote:
> >Hi Andrew,
> >
> >
> >On Thu, Jul 24, 2014 at 04:47:21PM -0700, Andrew Duggan wrote:
> >>RMI4 Function 0x30 provides support for GPIOs, LEDs and mechanical
> >>buttons.  In particular, the mechanical button support is used in
> >>an increasing number of touchpads.
> >>
> >I was reading the spec for F30 and it looks to me that instead instead of basic
> >keymap it should actually implement a gpio chip plus LED devices (probably
> >later). Then, if GPIOs are indeed attached to buttons one can use standard
> >gpio_keys driver to create input device.
> 
> The most common use of F30 is handling input from the tact switch on
> clickpads. Since the tact switch is wired up to the touch
> controller, it's the touch controller that handles the GPIO. The
> touch controller then asserts attention to the host, which then
> issues reads to see what interrupted, and then reads the F30 data
> register to get the state of the GPIO. Would gpio chip work with
> this setup? After looking at gpio chip a little bit I'm not really
> seeing how that would work. It looks like to work with gpio_keys
> each button would need it's own irq? I couldn't find an example of a
> driver doing something similar, but if there is one could you point
> me to it?
> 
> For touchpad buttons we know based on convention which GPIOs
> represent which buttons. In the case of touchpads we can avoid
> creating a button map in the platform data. For touchpads we also
> want to report the input events for F30 from the same input device
> which is reporting finger data. Benjamin's patchset contains a patch
> which allows for a unified input device which will allow more then
> one function to use the same input device.
> 
> The F30 spec is fairly generic so it could be used for things
> besides the touchpad buttons and we might want to report events
> independently of finger position. However, besides touchpad LEDs I'm
> not sure F30 has ever been used for other applications in production
> so I'm not sure its worth implementing something more generic at
> this time.

OK, fair enough. I'll have to take another look then - the details are
quite hazy ;)

> 
> >Thanks.
> >
> 
> Also, the fact that it took me over a year to reply to these
> comments highlights that we at Synaptics have been inconsistent in
> our effort to get the synaptics-rmi4 driver upstreamed. I think it's
> about time we have a single upstreamed driver which can support all
> of our RMI devices so I'm willing do more on behalf of Synaptics to
> help get it upstreamed.
> 
> Thanks,
> Andrew

Thanks.

-- 
Dmitry