linux-kernel - [PATCH 3.16 186/346] iio: adc: at91: unbreak channel adc channel 3

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Message-ID: <lsq.1479082460.21238371@decadent.org.uk>
Date:   Mon, 14 Nov 2016 00:14:20 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Anders Darander" <anders@...rgestorm.se>,
        "Alexandre Belloni" <alexandre.belloni@...e-electrons.com>,
        "Jonathan Cameron" <jic23@...nel.org>
Subject: [PATCH 3.16 186/346] iio: adc: at91: unbreak channel adc channel 3

3.16.39-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Anders Darander <anders@...rgestorm.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 <anders@...rgestorm.se>
Acked-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Signed-off-by: Jonathan Cameron <jic23@...nel.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 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