From e85bb0beb6498c0dffe18a2f1f16d575bc175c32 Mon Sep 17 00:00:00 2001
From: Aditya Pakki <pakki001@umn.edu>
Date: Mon, 7 Jan 2019 11:53:59 -0800
Subject: [PATCH] Input: ad7879 - add check for read errors in interrupt

regmap_bulk_read() can return a non zero value on failure. The fix checks
if the function call succeeded before calling mod_timer. The issue was
identified by a static analysis tool.

Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/input/touchscreen/ad7879.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/input/touchscreen/ad7879.c b/drivers/input/touchscreen/ad7879.c
index 6fa714c587b4f..3a016f43fb856 100644
--- a/drivers/input/touchscreen/ad7879.c
+++ b/drivers/input/touchscreen/ad7879.c
@@ -246,11 +246,14 @@ static void ad7879_timer(struct timer_list *t)
 static irqreturn_t ad7879_irq(int irq, void *handle)
 {
 	struct ad7879 *ts = handle;
+	int error;
 
-	regmap_bulk_read(ts->regmap, AD7879_REG_XPLUS,
-			 ts->conversion_data, AD7879_NR_SENSE);
-
-	if (!ad7879_report(ts))
+	error = regmap_bulk_read(ts->regmap, AD7879_REG_XPLUS,
+				 ts->conversion_data, AD7879_NR_SENSE);
+	if (error)
+		dev_err_ratelimited(ts->dev, "failed to read %#02x: %d\n",
+				    AD7879_REG_XPLUS, error);
+	else if (!ad7879_report(ts))
 		mod_timer(&ts->timer, jiffies + TS_PEN_UP_TIMEOUT);
 
 	return IRQ_HANDLED;
-- 
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