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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Dave Stevenson <dave.stevenson@raspberrypi.com>,
        Stefan Wahren <stefan.wahren@i2se.com>,
        Maxime Ripard <maxime@cerno.tech>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 40/62] drm/panel/raspberrypi-touchscreen: Avoid NULL deref if not initialised
Date:   Tue, 26 Apr 2022 10:21:20 +0200
Message-Id: <20220426081738.370466024@linuxfoundation.org>
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From: Dave Stevenson <dave.stevenson@raspberrypi.com>

[ Upstream commit f92055ae0acb035891e988ce345d6b81a0316423 ]

If a call to rpi_touchscreen_i2c_write from rpi_touchscreen_probe
fails before mipi_dsi_device_register_full is called, then
in trying to log the error message if uses ts->dsi->dev when
it is still NULL.

Use ts->i2c->dev instead, which is initialised earlier in probe.

Fixes: 2f733d6194bd ("drm/panel: Add support for the Raspberry Pi 7" Touchscreen.")
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220415162513.42190-2-stefan.wahren@i2se.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
index bdb4d59c8127..6906f522521d 100644
--- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
+++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
@@ -232,7 +232,7 @@ static void rpi_touchscreen_i2c_write(struct rpi_touchscreen *ts,
 
 	ret = i2c_smbus_write_byte_data(ts->i2c, reg, val);
 	if (ret)
-		dev_err(&ts->dsi->dev, "I2C write failed: %d\n", ret);
+		dev_err(&ts->i2c->dev, "I2C write failed: %d\n", ret);
 }
 
 static int rpi_touchscreen_write(struct rpi_touchscreen *ts, u16 reg, u32 val)
-- 
2.35.1