release/5.2.40/media-v4l2-device.h-Explicitly-compare-grp-id-mask-t.patch

From c66cb9281af1dce7a8f32a14af5429a0d1aac941 Mon Sep 17 00:00:00 2001
From: Nathan Chancellor <natechancellor@gmail.com>
Date: Sun, 8 Dec 2019 22:11:40 +0100
Subject: [PATCH] media: v4l2-device.h: Explicitly compare grp{id,mask} to zero
 in v4l2_device macros

commit afb34781620274236bd9fc9246e22f6963ef5262 upstream.

When building with Clang + -Wtautological-constant-compare, several of
the ivtv and cx18 drivers warn along the lines of:

 drivers/media/pci/cx18/cx18-driver.c:1005:21: warning: converting the
 result of '<<' to a boolean always evaluates to true
 [-Wtautological-constant-compare]
                         cx18_call_hw(cx, CX18_HW_GPIO_RESET_CTRL,
                                         ^
 drivers/media/pci/cx18/cx18-cards.h:18:37: note: expanded from macro
 'CX18_HW_GPIO_RESET_CTRL'
 #define CX18_HW_GPIO_RESET_CTRL         (1 << 6)
                                           ^
 1 warning generated.

This warning happens because the shift operation is implicitly converted
to a boolean in v4l2_device_mask_call_all before being negated. This can
be solved by just comparing the mask result to 0 explicitly so that
there is no boolean conversion. The ultimate goal is to enable
-Wtautological-compare globally because there are several subwarnings
that would be helpful to have.

For visual consistency and avoidance of these warnings in the future,
all of the implicitly boolean conversions in the v4l2_device macros
are converted to explicit ones as well.

Link: https://github.com/ClangBuiltLinux/linux/issues/752

Reviewed-by: Ezequiel Garcia <ezequiel@collabora.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/include/media/v4l2-device.h b/include/media/v4l2-device.h
index e0b8f2602670..a0e93f0ef62a 100644
--- a/include/media/v4l2-device.h
+++ b/include/media/v4l2-device.h
@@ -371,7 +371,7 @@ static inline bool v4l2_device_supports_requests(struct v4l2_device *v4l2_dev)
 		struct v4l2_subdev *__sd;				\
 									\
 		__v4l2_device_call_subdevs_p(v4l2_dev, __sd,		\
-			!(grpid) || __sd->grp_id == (grpid), o, f ,	\
+			(grpid) == 0 || __sd->grp_id == (grpid), o, f ,	\
 			##args);					\
 	} while (0)
 
@@ -403,7 +403,7 @@ static inline bool v4l2_device_supports_requests(struct v4l2_device *v4l2_dev)
 ({									\
 	struct v4l2_subdev *__sd;					\
 	__v4l2_device_call_subdevs_until_err_p(v4l2_dev, __sd,		\
-			!(grpid) || __sd->grp_id == (grpid), o, f ,	\
+			(grpid) == 0 || __sd->grp_id == (grpid), o, f ,	\
 			##args);					\
 })
 
@@ -431,8 +431,8 @@ static inline bool v4l2_device_supports_requests(struct v4l2_device *v4l2_dev)
 		struct v4l2_subdev *__sd;				\
 									\
 		__v4l2_device_call_subdevs_p(v4l2_dev, __sd,		\
-			!(grpmsk) || (__sd->grp_id & (grpmsk)), o, f ,	\
-			##args);					\
+			(grpmsk) == 0 || (__sd->grp_id & (grpmsk)), o,	\
+			f , ##args);					\
 	} while (0)
 
 /**
@@ -462,8 +462,8 @@ static inline bool v4l2_device_supports_requests(struct v4l2_device *v4l2_dev)
 ({									\
 	struct v4l2_subdev *__sd;					\
 	__v4l2_device_call_subdevs_until_err_p(v4l2_dev, __sd,		\
-			!(grpmsk) || (__sd->grp_id & (grpmsk)), o, f ,	\
-			##args);					\
+			(grpmsk) == 0 || (__sd->grp_id & (grpmsk)), o,	\
+			f , ##args);					\
 })
 
 
-- 
2.7.4