[PATCH 4.9 26/31] Input: touchscreen - avoid bitwise vs logical OR warning

Greg Kroah-Hartman
2021-12-20T14:38:58Z

From: Nathan Chancellor <nathan@kernel.org>

commit a02dcde595f7cbd240ccd64de96034ad91cffc40 upstream.

A new warning in clang points out a few places in this driver where a
bitwise OR is being used with boolean types:

drivers/input/touchscreen.c:81:17: warning: use of bitwise '|' with boolean operands [-Wbitwise-instead-of-logical]
data_present = touchscreen_get_prop_u32(dev, "touchscreen-min-x",
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This use of a bitwise OR is intentional, as bitwise operations do not
short circuit, which allows all the calls to touchscreen_get_prop_u32()
to happen so that the last parameter is initialized while coalescing the
results of the calls to make a decision after they are all evaluated.

To make this clearer to the compiler, use the '|=' operator to assign
the result of each touchscreen_get_prop_u32() call to data_present,
which keeps the meaning of the code the same but makes it obvious that
every one of these calls is expected to happen.

Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20211014205757.3474635-1-nathan@kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/input/touchscreen/of_touchscreen.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

--- a/drivers/input/touchscreen/of_touchscreen.c
+++ b/drivers/input/touchscreen/of_touchscreen.c
@@ -79,8 +79,8 @@ void touchscreen_parse_properties(struct
data_present = touchscreen_get_prop_u32(dev, "touchscreen-size-x",
input_abs_get_max(input,
axis) + 1,
- &maximum) |
- touchscreen_get_prop_u32(dev, "touchscreen-fuzz-x",
+ &maximum);
+ data_present |= touchscreen_get_prop_u32(dev, "touchscreen-fuzz-x",
input_abs_get_fuzz(input, axis),
&fuzz);
if (data_present)
@@ -90,8 +90,8 @@ void touchscreen_parse_properties(struct
data_present = touchscreen_get_prop_u32(dev, "touchscreen-size-y",
input_abs_get_max(input,
axis) + 1,
- &maximum) |
- touchscreen_get_prop_u32(dev, "touchscreen-fuzz-y",
+ &maximum);
+ data_present |= touchscreen_get_prop_u32(dev, "touchscreen-fuzz-y",
input_abs_get_fuzz(input, axis),
&fuzz);
if (data_present)
@@ -101,11 +101,11 @@ void touchscreen_parse_properties(struct
data_present = touchscreen_get_prop_u32(dev,
"touchscreen-max-pressure",
input_abs_get_max(input, axis),
- &maximum) |
- touchscreen_get_prop_u32(dev,
- "touchscreen-fuzz-pressure",
- input_abs_get_fuzz(input, axis),
- &fuzz);
+ &maximum);
+ data_present |= touchscreen_get_prop_u32(dev,
+ "touchscreen-fuzz-pressure",
+ input_abs_get_fuzz(input, axis),
+ &fuzz);
if (data_present)
touchscreen_set_params(input, axis, maximum, fuzz);