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Input: usbtouchscreen - avoid unresponsive TSC-30 touch screen

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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.

Cc: stable@vger.kernel.org
Suggested-by: Jakob Mustafa <jakob.mustafa@bytecmed.com>
Signed-off-by: Bernhard Bender <bernhard.bender@bytecmed.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
This commit is contained in:
Bernhard Bender 2015-07-23 13:58:08 -07:00 committed by Dmitry Torokhov
parent d98399e688
commit 968491709e
1 changed files with 3 additions and 0 deletions
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3
drivers/input/touchscreen/usbtouchscreen.c
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@ -627,6 +627,9 @@ static int dmc_tsc10_init(struct usbtouch_usb *usbtouch)
goto err_out; goto err_out;
} }
/* TSC-25 data sheet specifies a delay after the RESET command */
msleep(150);
/* set coordinate output rate */ /* set coordinate output rate */
buf[0] = buf[1] = 0xFF; buf[0] = buf[1] = 0xFF;
ret = usb_control_msg(dev, usb_rcvctrlpipe (dev, 0), ret = usb_control_msg(dev, usb_rcvctrlpipe (dev, 0),