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| author | Bernhard Bender <bernhard.bender@bytecmed.com> | 2015-07-23 13:58:08 -0700 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2015-08-12 16:33:23 +0200 |
| commit | 340f2018234cb04ac73095f3629fb57d890a0638 (patch) | |
| tree | 357d430c9abfb1a6bb98841aa252a8371c925038 /drivers/input | |
| parent | b61d6d5726d25826d4c0f7d47d9053f4c47c7628 (diff) | |
| download | lwn-340f2018234cb04ac73095f3629fb57d890a0638.tar.gz lwn-340f2018234cb04ac73095f3629fb57d890a0638.zip | |
Input: usbtouchscreen - avoid unresponsive TSC-30 touch screen
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>
Diffstat (limited to 'drivers/input')
| -rw-r--r-- | drivers/input/touchscreen/usbtouchscreen.c | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/drivers/input/touchscreen/usbtouchscreen.c b/drivers/input/touchscreen/usbtouchscreen.c index 73fd6642b681..e26a7c396de6 100644 --- a/drivers/input/touchscreen/usbtouchscreen.c +++ b/drivers/input/touchscreen/usbtouchscreen.c @@ -528,6 +528,9 @@ 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), |