| From | Ben Hutchings <> | Date | Mon, 10 Aug 2015 12:12:31 +0200 | Subject | [PATCH 3.2 102/110] Input: usbtouchscreen - avoid unresponsive TSC-30 touch screen |
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3.2.71-rc1 review patch. If anyone has any objections, please let me know.
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From: Bernhard Bender <bernhard.bender@bytecmed.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@bytecmed.com> Signed-off-by: Bernhard Bender <bernhard.bender@bytecmed.com> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- drivers/input/touchscreen/usbtouchscreen.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/drivers/input/touchscreen/usbtouchscreen.c +++ b/drivers/input/touchscreen/usbtouchscreen.c @@ -528,6 +528,9 @@ static int dmc_tsc10_init(struct usbtouc 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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