From 7e92f2bdf04811093aa212caa0ee8b45bb5a7be6 Mon Sep 17 00:00:00 2001 From: Dave Stevenson Date: Wed, 8 Sep 2021 14:21:38 +0100 Subject: [PATCH 0300/1085] 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 --- drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c +++ b/drivers/gpu/drm/panel/panel-raspberrypi-touchscreen.c @@ -295,13 +295,14 @@ static int rpi_touchscreen_noop(struct d 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; }