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Subject[Update][PATCH 4/5] PM / input / touchscreen: Make st1232 use device PM QoS constraints
Date
From: Rafael J. Wysocki <rjw@sisk.pl>

Make the st1232 driver use dev_pm_qos_add_ancestor_request() to
add a device PM QoS latency constraint for the controller it
depends on, so that the controller won't go into an overly deep
low-power state when the touchscreen has to be particularly
responsive (e.g. when the user moves his or her finger on it).

This change is based on a prototype patch from Guennadi Liakhovetski.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
drivers/input/touchscreen/st1232.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
Index: linux/drivers/input/touchscreen/st1232.c
===================================================================
--- linux.orig/drivers/input/touchscreen/st1232.c
+++ linux/drivers/input/touchscreen/st1232.c
@@ -23,6 +23,7 @@
#include <linux/input.h>
#include <linux/interrupt.h>
#include <linux/module.h>
+#include <linux/pm_qos.h>
#include <linux/slab.h>
#include <linux/types.h>

@@ -46,6 +47,7 @@ struct st1232_ts_data {
struct i2c_client *client;
struct input_dev *input_dev;
struct st1232_ts_finger finger[MAX_FINGERS];
+ struct dev_pm_qos_request low_latency_req;
};

static int st1232_ts_read_data(struct st1232_ts_data *ts)
@@ -118,8 +120,17 @@ static irqreturn_t st1232_ts_irq_handler
}

/* SYN_MT_REPORT only if no contact */
- if (!count)
+ if (!count) {
input_mt_sync(input_dev);
+ if (ts->low_latency_req.dev) {
+ dev_pm_qos_remove_request(&ts->low_latency_req);
+ ts->low_latency_req.dev = NULL;
+ }
+ } else if (!ts->low_latency_req.dev) {
+ /* First contact, request 100 us latency. */
+ dev_pm_qos_add_ancestor_request(&ts->client->dev,
+ &ts->low_latency_req, 100);
+ }

/* SYN_REPORT */
input_sync(input_dev);


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