From: H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> commit 2d4100632fa1947bf3e8d7a091e94e2cf21923af upstream. omap_w1_read_byte() should return -1 (or 0xff) in case of error (e.g. missing battery). The code accidentially overwrites the variable ret and not val, which is returned. So it will return the initial value 0 instead of -1. Fixes: 27d13da8782a ("w1: omap-hdq: Simplify driver with PM runtime autosuspend") Cc: stable@xxxxxxxxxxxxxxx # v5.6+ Acked-by: Tony Lindgren <tony@xxxxxxxxxxx> Signed-off-by: H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/b2c2192b461fbb9b8e9bea4ad514a49557a7210b.1590255176.git.hns@xxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/w1/masters/omap_hdq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/w1/masters/omap_hdq.c +++ b/drivers/w1/masters/omap_hdq.c @@ -464,7 +464,7 @@ static u8 omap_w1_read_byte(void *_hdq) ret = hdq_read_byte(hdq_data, &val); if (ret) - ret = -1; + val = -1; pm_runtime_mark_last_busy(hdq_data->dev); pm_runtime_put_autosuspend(hdq_data->dev);