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From: Nathan Chancellor <nathan@kernel.org>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
	linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
	llvm@lists.linux.dev, Nathan Chancellor <nathan@kernel.org>
Subject: [PATCH] Input: touchscreen - Avoid bitwise vs logical OR warning
Date: Thu, 14 Oct 2021 13:57:57 -0700	[thread overview]
Message-ID: <20211014205757.3474635-1-nathan@kernel.org> (raw)

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.

Link: https://github.com/ClangBuiltLinux/linux/issues/1472
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 drivers/input/touchscreen.c | 42 ++++++++++++++++++-------------------
 1 file changed, 21 insertions(+), 21 deletions(-)

diff --git a/drivers/input/touchscreen.c b/drivers/input/touchscreen.c
index dd18cb917c4d..4620e20d0190 100644
--- a/drivers/input/touchscreen.c
+++ b/drivers/input/touchscreen.c
@@ -80,27 +80,27 @@ void touchscreen_parse_properties(struct input_dev *input, bool multitouch,
 
 	data_present = touchscreen_get_prop_u32(dev, "touchscreen-min-x",
 						input_abs_get_min(input, axis_x),
-						&minimum) |
-		       touchscreen_get_prop_u32(dev, "touchscreen-size-x",
-						input_abs_get_max(input,
-								  axis_x) + 1,
-						&maximum) |
-		       touchscreen_get_prop_u32(dev, "touchscreen-fuzz-x",
-						input_abs_get_fuzz(input, axis_x),
-						&fuzz);
+						&minimum);
+	data_present |= touchscreen_get_prop_u32(dev, "touchscreen-size-x",
+						 input_abs_get_max(input,
+								   axis_x) + 1,
+						 &maximum);
+	data_present |= touchscreen_get_prop_u32(dev, "touchscreen-fuzz-x",
+						 input_abs_get_fuzz(input, axis_x),
+						 &fuzz);
 	if (data_present)
 		touchscreen_set_params(input, axis_x, minimum, maximum - 1, fuzz);
 
 	data_present = touchscreen_get_prop_u32(dev, "touchscreen-min-y",
 						input_abs_get_min(input, axis_y),
-						&minimum) |
-		       touchscreen_get_prop_u32(dev, "touchscreen-size-y",
-						input_abs_get_max(input,
-								  axis_y) + 1,
-						&maximum) |
-		       touchscreen_get_prop_u32(dev, "touchscreen-fuzz-y",
-						input_abs_get_fuzz(input, axis_y),
-						&fuzz);
+						&minimum);
+	data_present |= touchscreen_get_prop_u32(dev, "touchscreen-size-y",
+						 input_abs_get_max(input,
+								   axis_y) + 1,
+						 &maximum);
+	data_present |= touchscreen_get_prop_u32(dev, "touchscreen-fuzz-y",
+						 input_abs_get_fuzz(input, axis_y),
+						 &fuzz);
 	if (data_present)
 		touchscreen_set_params(input, axis_y, minimum, maximum - 1, fuzz);
 
@@ -108,11 +108,11 @@ void touchscreen_parse_properties(struct input_dev *input, bool multitouch,
 	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, 0, maximum, fuzz);
 

base-commit: a41392e0877a271007e9209e63c34cab7527eb43
-- 
2.33.1.637.gf443b226ca


             reply	other threads:[~2021-10-14 20:58 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-14 20:57 Nathan Chancellor [this message]
2021-10-14 21:02 ` Nick Desaulniers

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