-----Original Message-----
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Sent: 2020年3月10日 12:27
To: BOUGH CHEN <haibo.chen@nxp.com>
Cc: linux-input@vger.kernel.org; dl-linux-imx <redacted>
Subject: Re: [PATCH 2/2] input: egalax_ts: free irq resource before request
the line as GPIO

On Tue, Feb 11, 2020 at 04:41:12PM +0800, haibo.chen@nxp.com wrote:

quoted

From: Haibo Chen <haibo.chen@nxp.com>

If GPIO is connected to an IRQ then it should not request it as GPIO
function only when free its IRQ resource.

Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
---
 drivers/input/touchscreen/egalax_ts.c | 44
+++++++++++++++++++--------
 1 file changed, 31 insertions(+), 13 deletions(-)

diff --git a/drivers/input/touchscreen/egalax_ts.c

b/drivers/input/touchscreen/egalax_ts.c
index 5e35ca5edc7b..c7983104a0b9 100644

--- a/drivers/input/touchscreen/egalax_ts.c
+++ b/drivers/input/touchscreen/egalax_ts.c

@@ -116,6 +116,26 @@ static irqreturn_t egalax_ts_interrupt(int irq, void

*dev_id)

quoted

 	return IRQ_HANDLED;
 }

+static int egalax_irq_request(struct egalax_ts *ts) {
+	int ret;
+	struct i2c_client *client = ts->client;
+
+	ret = devm_request_threaded_irq(&client->dev, client->irq, NULL,
+					egalax_ts_interrupt,
+					IRQF_TRIGGER_LOW | IRQF_ONESHOT,
+					"egalax_ts", ts);
+	if (ret < 0)
+		dev_err(&client->dev, "Failed to register interrupt\n");
+
+	return ret;
+}
+
+static void egalax_free_irq(struct egalax_ts *ts) {
+	devm_free_irq(&ts->client->dev, ts->client->irq, ts); }
+
 /* wake up controller by an falling edge of interrupt gpio.  */
static int egalax_wake_up_device(struct i2c_client *client)  { @@
-225,19 +245,15 @@ static int egalax_ts_probe(struct i2c_client *client,
 			     ABS_MT_POSITION_Y, 0, EGALAX_MAX_Y, 0, 0);
 	input_mt_init_slots(input_dev, MAX_SUPPORT_POINTS, 0);

-	error = devm_request_threaded_irq(&client->dev, client->irq, NULL,
-					  egalax_ts_interrupt,
-					  IRQF_TRIGGER_LOW | IRQF_ONESHOT,
-					  "egalax_ts", ts);
-	if (error < 0) {
-		dev_err(&client->dev, "Failed to register interrupt\n");
+	error = egalax_irq_request(ts);
+	if (error)
 		return error;
-	}

 	error = input_register_device(ts->input_dev);
 	if (error)
 		return error;

+	i2c_set_clientdata(client, ts);
 	return 0;
 }

@@ -253,11 +269,10 @@ static int __maybe_unused

egalax_ts_suspend(struct device *dev)

quoted

 		0x3, 0x6, 0xa, 0x3, 0x36, 0x3f, 0x2, 0, 0, 0
 	};
 	struct i2c_client *client = to_i2c_client(dev);
+	struct egalax_ts *ts = i2c_get_clientdata(client);
 	int ret;

-	if (device_may_wakeup(dev))
-		return enable_irq_wake(client->irq);
-

Why are you removing handling of the interrupt as a wakeup source if device
is configured for wakeup? I guess it is a noop and I2C core does it for us on
newer kernels anyways, but such cleanup should be in  a separate patch.
Still, you do not want to put the controller to sleep if it is supposed to be a
wakeup source.

Agree, I will keep the code there. I will add a code in the egalax_ts_resume(), if the device my wakeup, skip egalax_wake_up_device(), return directly. 

quoted

+	egalax_free_irq(ts);

It sounds to me you want simply disable interrupts in suspend. Does not
calling disable_irq() here suffice?

Here why I want to disable interrupts here is because in the newest gpio system, if the gpio is request as an irq, it can't be request as a gpio anymore.
In the function egalax_wake_up_device(), we need to request the irq pin as a gpio for a while, generate a signal to wake up the device. So before request the pad as gpio, need first free irq resource.
Seems there are two methods, one is free irq in egalax_ts_suspend(), anther is just free irq in egalax_ts_suspend(), after the gpio operation done, request the irq resource back, which one do you prefer?

Best Regards
Haibo Chen

Thanks.

--
Dmitry