linux-kernel - RE: [PATCH v2 2/4] da850-evm: add UI Expander pushbuttons

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Message-ID: <B85A65D85D7EB246BE421B3FB0FBB59302477EA939@dbde02.ent.ti.com>
Date:	Fri, 19 Nov 2010 15:28:00 +0530
From:	"Nori, Sekhar" <nsekhar@...com>
To:	Ben Gardiner <bengardiner@...ometrics.ca>,
	Kevin Hilman <khilman@...prootsystems.com>,
	"davinci-linux-open-source@...ux.davincidsp.com" 
	<davinci-linux-open-source@...ux.davincidsp.com>,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>
CC:	"Govindarajan, Sriramakrishnan" <srk@...com>,
	Paul Mundt <lethal@...ux-sh.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Alexander Clouter <alex@...riz.org.uk>,
	Chris Cordahi <christophercordahi@...ometrics.ca>
Subject: RE: [PATCH v2 2/4] da850-evm: add UI Expander pushbuttons

Hi Ben,

Thanks for the patches. Some comments/questions below:

On Wed, Nov 17, 2010 at 01:09:35, Ben Gardiner wrote:
> This patch adds EV_KEYs for each of the 8 pushbuttons on the UI board via a
> gpio-key device.
>
> The expander is a tca6416; it controls the SEL_{A,B,C} lines which enable and
> disable the peripherals found on the UI board in addition to the 8 pushbuttons
> mentioned above. The reason the existing tca6416-keypad driver is not employed
> is because there was no aparent way to keep the gpio lines used as
> SEL_{A,B,C} registered while simultaneously registering the pushbuttons as a
> tca6416-keypad instance.
>
> Some experimentation with the polling interval was performed; we were searching
> for the largest polling interval that did not affect the feel of the
> responsiveness of the buttons. It is very subjective but 200ms seems to be a
> good value that accepts firm pushes but rejects very light ones. The key values
> assigned to the buttons were arbitrarily chosen to be F1-F8.
>
> Signed-off-by: Ben Gardiner <bengardiner@...ometrics.ca>
> Reviewed-by: Chris Cordahi <christophercordahi@...ometrics.ca>
> CC: Govindarajan, Sriramakrishnan <srk@...com>
>
> ---
>
> Changes since v1:
>  * set INPUT_POLLDEV default for DA850_EVM machine, but don't select it
>    unconditionally

I didn't see the v1 posting (wonder why), but why is this
required? Why cant we depend on this being selected from
Device Drivers->Input device support in menuconfig?

[...]

> @@ -349,6 +421,10 @@ static struct i2c_board_info __initdata da850_evm_i2c_devices[] = {
>       {
>               I2C_BOARD_INFO("tca6416", 0x20),
>               .platform_data = &da850_evm_ui_expander_info,
> +             /*
> +              * TODO : populate at runtime using
> +              * .irq = gpio_to_irq(GPIO_TO_PIN(2,7)),
> +              */

You seem to be adding this in this patch and removing
in 4/4.

Thanks,
Sekhar

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