linux-kernel - [PATCH] input: touchscreen: add delay time to device power on

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Message-Id: <20190710025859.6025-1-crag0715@gmail.com>
Date:   Wed, 10 Jul 2019 10:58:59 +0800
From:   crag0715@...il.com
To:     unlisted-recipients:; (no To-header on input)
Cc:     mario_limonciello@...l.com, chrome.os.engineering@...l.com,
        "Crag.Wang" <crag.wang@...l.com>, Sangwon Jee <jeesw@...fas.com>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] input: touchscreen: add delay time to device power on

From: "Crag.Wang" <crag.wang@...l.com>

Delay time for MELFAS MIP4 controller is required at power on stage
regardless the existence of GPIO consumer lookup from devicetree or
ACPI device table.

There is an issue if GPIO ce is undefined in the ACPI results no delay
time for deive power on, the controller ended up in an abnormal state.

TEST=echo i2c-MLFS0000:00 > /sys/bus/i2c/drivers/mip4_ts/unbind
     verify the touch function is off

     echo i2c-MLFS0000:00 > /sys/bus/i2c/drivers/mip4_ts/bind
     verify the touch function is on

Signed-off-by: Crag.Wang <crag.wang@...l.com>
---
 drivers/input/touchscreen/melfas_mip4.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/input/touchscreen/melfas_mip4.c b/drivers/input/touchscreen/melfas_mip4.c
index 430a2bc5f7ca..8e803658fb43 100644
--- a/drivers/input/touchscreen/melfas_mip4.c
+++ b/drivers/input/touchscreen/melfas_mip4.c
@@ -374,12 +374,11 @@ static int mip4_query_device(struct mip4_ts *ts)
 
 static int mip4_power_on(struct mip4_ts *ts)
 {
-	if (ts->gpio_ce) {
+	if (ts->gpio_ce)
 		gpiod_set_value_cansleep(ts->gpio_ce, 1);
 
-		/* Booting delay : 200~300ms */
-		usleep_range(200 * 1000, 300 * 1000);
-	}
+	/* Booting delay : 200~300ms */
+	usleep_range(200 * 1000, 300 * 1000);
 
 	return 0;
 }
-- 
2.20.1