From aef36d8fa9561689ff503d3873a2cfbeabff14f2 Mon Sep 17 00:00:00 2001
From: Fabien Parent <fparent@baylibre.com>
Date: Fri, 18 Oct 2019 19:32:13 +0200
Subject: [PATCH] i2c: mt65xx: fix NULL ptr dereference

commit 62931ac2f9015ea38d80494ec37658ab3df6a6d7 upstream.

Since commit abf4923e97c3 ("i2c: mediatek: disable zero-length transfers
for mt8183"), there is a NULL pointer dereference for all the SoCs
that don't have any quirk. mtk_i2c_functionality is not checking that
the quirks pointer is not NULL before starting to use it.

This commit add a call to i2c_check_quirks which will check whether
the quirks pointer is set, and if so will check if the IP has the
NO_ZERO_LEN quirk.

Fixes: abf4923e97c3 ("i2c: mediatek: disable zero-length transfers for mt8183")
Signed-off-by: Fabien Parent <fparent@baylibre.com>
Reviewed-by: Cengiz Can <cengiz@kernel.wtf>
Reviewed-by: Hsin-Yi Wang <hsinyi@chromium.org>
Tested-by: Ulrich Hecht <uli@fpond.eu>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
index 29eae1bf4f86..2152ec5f535c 100644
--- a/drivers/i2c/busses/i2c-mt65xx.c
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -875,7 +875,7 @@ static irqreturn_t mtk_i2c_irq(int irqno, void *dev_id)
 
 static u32 mtk_i2c_functionality(struct i2c_adapter *adap)
 {
-	if (adap->quirks->flags & I2C_AQ_NO_ZERO_LEN)
+	if (i2c_check_quirks(adap, I2C_AQ_NO_ZERO_LEN))
 		return I2C_FUNC_I2C |
 			(I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
 	else
-- 
2.7.4