From: Dave Stevenson <dave.stevenson@raspberrypi.com>
Date: Wed, 8 Sep 2021 13:21:38 +0000 (+0100)
Subject: drm/panel/raspberrypi-touchscreen: Handle I2C errors.
X-Git-Tag: accepted/tizen/unified/20230118.172025~1082
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=d5013c6f3d743ec5edc06a5dfa9c8727ca3c917d;p=platform%2Fkernel%2Flinux-rpi.git

drm/panel/raspberrypi-touchscreen: Handle I2C errors.

rpi_touchscreen_i2c_read returns any errors from i2c_transfer,
or the 8 bit received value.
Check for error values before trying to process the data as
valid.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---

diff --git a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
index bd15c2f2e247..329341bcfa50 100644
--- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
+++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c
@@ -296,13 +296,14 @@ static int rpi_touchscreen_noop(struct drm_panel *panel)
 static int rpi_touchscreen_prepare(struct drm_panel *panel)
 {
 	struct rpi_touchscreen *ts = panel_to_ts(panel);
-	int i;
+	int i, data;
 
 	rpi_touchscreen_i2c_write(ts, REG_POWERON, 1);
 	usleep_range(20000, 25000);
 	/* Wait for nPWRDWN to go low to indicate poweron is done. */
 	for (i = 0; i < 100; i++) {
-		if (rpi_touchscreen_i2c_read(ts, REG_PORTB) & 1)
+		data = rpi_touchscreen_i2c_read(ts, REG_PORTB);
+		if (data >= 0 && (data & 1))
 			break;
 	}