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Message-Id: <1440713521-5906-45-git-send-email-kamal@canonical.com>
Date: Thu, 27 Aug 2015 15:10:35 -0700
From: Kamal Mostafa <kamal@...onical.com>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
kernel-team@...ts.ubuntu.com
Cc: Bernhard Bender <bernhard.bender@...ecmed.com>,
Dmitry Torokhov <dmitry.torokhov@...il.com>,
Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 044/130] Input: usbtouchscreen - avoid unresponsive TSC-30 touch screen
3.19.8-ckt6 -stable review patch. If anyone has any objections, please let me know.
------------------
From: Bernhard Bender <bernhard.bender@...ecmed.com>
commit 968491709e5b1aaf429428814fff3d932fa90b60 upstream.
This patch fixes a problem in the usbtouchscreen driver for DMC TSC-30
touch screen. Due to a missing delay between the RESET and SET_RATE
commands, the touch screen may become unresponsive during system startup or
driver loading.
According to the DMC documentation, a delay is needed after the RESET
command to allow the chip to complete its internal initialization. As this
delay is not guaranteed, we had a system where the touch screen
occasionally did not send any touch data. There was no other indication of
the problem.
The patch fixes the problem by adding a 150ms delay between the RESET and
SET_RATE commands.
Suggested-by: Jakob Mustafa <jakob.mustafa@...ecmed.com>
Signed-off-by: Bernhard Bender <bernhard.bender@...ecmed.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
drivers/input/touchscreen/usbtouchscreen.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/input/touchscreen/usbtouchscreen.c b/drivers/input/touchscreen/usbtouchscreen.c
index a096633..c6f7e91 100644
--- a/drivers/input/touchscreen/usbtouchscreen.c
+++ b/drivers/input/touchscreen/usbtouchscreen.c
@@ -625,6 +625,9 @@ static int dmc_tsc10_init(struct usbtouch_usb *usbtouch)
goto err_out;
}
+ /* TSC-25 data sheet specifies a delay after the RESET command */
+ msleep(150);
+
/* set coordinate output rate */
buf[0] = buf[1] = 0xFF;
ret = usb_control_msg(dev, usb_rcvctrlpipe (dev, 0),
--
1.9.1
--
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