Commit 2670fc6f authored by Bernhard Bender's avatar Bernhard Bender Committed by Greg Kroah-Hartman

Input: usbtouchscreen - avoid unresponsive TSC-30 touch screen

commit 96849170 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: default avatarJakob Mustafa <jakob.mustafa@bytecmed.com>
Signed-off-by: default avatarBernhard Bender <bernhard.bender@bytecmed.com>
Signed-off-by: default avatarDmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent a8af704c
......@@ -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),
......
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