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

[Richard Röjfors]

On 7/24/09 8:00 PM, Dmitry Torokhov wrote:
> 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@xxxxxxxxxxxxxxx>
> > ---
> > 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.

You are right, I think we should leave the patch like below, just get 
rid of the unnecessary read during startup.

--Richard

Input: tsc2007: Do not read coordinated when probing driver

From: Richard Röjfors <richard.rojfors.ext@xxxxxxxxxxxxxxx>

Don't read coordinates during probe of the driver, just powering down 
the controller and wait for interrupts.


Signed-off-by: Richard Röjfors<richard.rojfors.ext@xxxxxxxxxxxxxxx>
---
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 1056)
@@ -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) */
@@ -190,8 +196,7 @@
 	tsc->tc.z1 = tsc2007_xfer(tsc, READ_Z1);
 	tsc->tc.z2 = tsc2007_xfer(tsc, READ_Z2);

-	/* power down */
-	tsc2007_xfer(tsc, PWRDOWN);
+	tsc2007_power_down(tsc);

 	return 0;
 }
@@ -305,7 +310,7 @@
 	input_set_abs_params(input_dev, ABS_Y, 0, MAX_12BIT, 0, 0);
 	input_set_abs_params(input_dev, ABS_PRESSURE, 0, MAX_12BIT, 0, 0);

-	tsc2007_read_values(ts);
+	tsc2007_power_down(ts);

 	ts->irq = client->irq;

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