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

Richard Röjfors
2009-07-24T19:37:31Z

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@mocean-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.
>

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@mocean-labs.com>

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@mocean-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 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;