From 672e78cab819ebe31e3b9b8abac367be8a110472 Mon Sep 17 00:00:00 2001 From: Nathan Chancellor Date: Mon, 10 Dec 2018 16:42:01 -0700 Subject: drm/amd/display: Pass app_tf by value rather than by reference Clang warns when an expression that equals zero is used as a null pointer constant (in lieu of NULL): drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:4435:3: warning: expression which evaluates to zero treated as a null pointer constant of type 'const enum color_transfer_func *' [-Wnon-literal-null-conversion] TRANSFER_FUNC_UNKNOWN, ^~~~~~~~~~~~~~~~~~~~~ 1 warning generated. This warning is caused by commit bb47de736661 ("drm/amdgpu: Set FreeSync state using drm VRR properties") and it could be solved by using NULL instead of TRANSFER_FUNC_UNKNOWN or casting TRANSFER_FUNC_UNKNOWN as a pointer. However, after looking into it, there doesn't appear to be a good reason to pass app_tf by reference as it is never mutated along the way. This is the only code path in which app_tf is used: mod_freesync_build_vrr_infopacket -> build_vrr_infopacket_v2 -> build_vrr_infopacket_fs2_data Neither mod_freesync_build_vrr_infopacket or build_vrr_infopacket_v2 modify app_tf's value and build_vrr_infopacket_fs2_data expects just the value so we can avoid dereferencing anything by just passing in app_tf's value to mod_freesync_build_vrr_infopacket and build_vrr_infopacket_v2. There is no functional change because build_vrr_infopacket_fs2_data doesn't do anything if TRANSFER_FUNC_UNKNOWN is passed to it, the same as not calling build_vrr_infopacket_fs2_data at all like before this change when NULL was used for app_tf. Reviewed-by: Harry Wentland Signed-off-by: Nathan Chancellor Signed-off-by: Alex Deucher --- drivers/gpu/drm/amd/display/modules/inc/mod_freesync.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/gpu/drm/amd/display/modules/inc') diff --git a/drivers/gpu/drm/amd/display/modules/inc/mod_freesync.h b/drivers/gpu/drm/amd/display/modules/inc/mod_freesync.h index 4222e403b151..dcef85994c45 100644 --- a/drivers/gpu/drm/amd/display/modules/inc/mod_freesync.h +++ b/drivers/gpu/drm/amd/display/modules/inc/mod_freesync.h @@ -145,7 +145,7 @@ void mod_freesync_build_vrr_infopacket(struct mod_freesync *mod_freesync, const struct dc_stream_state *stream, const struct mod_vrr_params *vrr, enum vrr_packet_type packet_type, - const enum color_transfer_func *app_tf, + enum color_transfer_func app_tf, struct dc_info_packet *infopacket); void mod_freesync_build_vrr_params(struct mod_freesync *mod_freesync, -- cgit v1.2.3