4.7-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Anders Darander <and...@chargestorm.se>

commit c2ab447454d498e709d9011c0f2d2945ee321f9b upstream.

The driver always assumes that an input device has been created when
reading channel 3. This causes a kernel panic when dereferencing
st->ts_input.

The change was introduced in
commit 84882b060301 ("iio: adc: at91_adc: Add support for touchscreens
without TSMR"). Earlier versions only entered that part of the if-else
statement if only the following flags are set:

AT91_ADC_IER_XRDY | AT91_ADC_IER_YRDY | AT91_ADC_IER_PRDY

Signed-off-by: Anders Darander <and...@chargestorm.se>
Acked-by: Alexandre Belloni <alexandre.bell...@free-electrons.com>
Signed-off-by: Jonathan Cameron <ji...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/iio/adc/at91_adc.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/iio/adc/at91_adc.c
+++ b/drivers/iio/adc/at91_adc.c
@@ -381,8 +381,8 @@ static irqreturn_t at91_adc_rl_interrupt
                st->ts_bufferedmeasure = false;
                input_report_key(st->ts_input, BTN_TOUCH, 0);
                input_sync(st->ts_input);
-       } else if (status & AT91_ADC_EOC(3)) {
-               /* Conversion finished */
+       } else if (status & AT91_ADC_EOC(3) && st->ts_input) {
+               /* Conversion finished and we've a touchscreen */
                if (st->ts_bufferedmeasure) {
                        /*
                         * Last measurement is always discarded, since it can


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