linux-kernel - Re: [PATCH 2/2] tsc2007: reduced number of I2C transfers

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Message-ID: <20090724180022.GA6477@dtor-d630.eng.vmware.com>
Date:	Fri, 24 Jul 2009 11:00:22 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Richard Röjfors 
	<richard.rojfors.ext@...ean-labs.com>
Cc:	linux-input@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	kwangwoo.lee@...il.com,
	Thierry Reding <thierry.reding@...onic-design.de>,
	Trilok Soni <soni.trilok@...il.com>
Subject: Re: [PATCH 2/2] tsc2007: reduced number of I2C transfers

On Fri, Jul 24, 2009 at 06:14:37PM +0200, Richard Röjfors wrote:
> Decreases the number of I2C transactions transferred by the driver.
> During probe we don't need to ask for the coordinates from the controller.
> When polling the controller we don't need to power down and enable IRQ  
> if we are going to poll again.
>
> Signed-off-by: Richard Röjfors <richard.rojfors.ext@...ean-labs.com>
> ---
> Index: linux-2.6.31-rc2/drivers/input/touchscreen/tsc2007.c
> ===================================================================
> --- linux-2.6.31-rc2/drivers/input/touchscreen/tsc2007.c	(revision 1040)
> +++ linux-2.6.31-rc2/drivers/input/touchscreen/tsc2007.c	(revision 1053)
> @@ -178,6 +178,12 @@
>  		ts->penstate = PEN_STATE_UP;
>  }
>
> +static void tsc2007_power_down(struct tsc2007 *tsc)
> +{
> +	/* power down */
> +	tsc2007_xfer(tsc, PWRDOWN);
> +}
> +
>  static int tsc2007_read_values(struct tsc2007 *tsc)
>  {
>  	/* y- still on; turn on only y+ (and ADC) */
> @@ -188,11 +194,8 @@
>
>  	/* turn y+ off, x- on; we'll use formula #1 */
>  	tsc->tc.z1 = tsc2007_xfer(tsc, READ_Z1);
> -	tsc->tc.z2 = tsc2007_xfer(tsc, READ_Z2);
> +	tsc->tc.z2 = tsc2007_xfer(tsc, READ_Z2 | TSC2007_POWER_OFF_IRQ_EN);

I think this leaves the controller powered on and with with PENIRQ
disabled.

-- 
Dmitry
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