The mod_freesync_build_vrr_infopacket() function uses rather obscure calling conventions, where an enum is passed in through a pointer, and a NULL pointer is expected to behave the same way as the zero-value (TRANSFER_FUNC_UNKNOWN).
Trying to build this with clang results in a warning:
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:4601:3: error: expression which evaluates to zero treated as a null pointer constant of type 'const enum color_transfer_func *' [-Werror,-Wnon-literal-null-conversion]
Passing it by value instead of by reference makes the code simpler and more conventional but should not change the behavior at all.
Fixes: c2791297013e ("drm/amd/display: Add color bit info to freesync infoframe") Signed-off-by: Arnd Bergmann arnd@arndb.de --- drivers/gpu/drm/amd/display/modules/freesync/freesync.c | 7 +++---- drivers/gpu/drm/amd/display/modules/inc/mod_freesync.h | 2 +- 2 files changed, 4 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c index 94a84bc57c7a..6f32fe129880 100644 --- a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c +++ b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c @@ -724,7 +724,7 @@ static void build_vrr_infopacket_v1(enum signal_type signal,
static void build_vrr_infopacket_v2(enum signal_type signal, const struct mod_vrr_params *vrr, - const enum color_transfer_func *app_tf, + const enum color_transfer_func app_tf, struct dc_info_packet *infopacket) { unsigned int payload_size = 0; @@ -732,8 +732,7 @@ static void build_vrr_infopacket_v2(enum signal_type signal, build_vrr_infopacket_header_v2(signal, infopacket, &payload_size); build_vrr_infopacket_data(vrr, infopacket);
- if (app_tf != NULL) - build_vrr_infopacket_fs2_data(*app_tf, infopacket); + build_vrr_infopacket_fs2_data(app_tf, infopacket);
build_vrr_infopacket_checksum(&payload_size, infopacket);
@@ -757,7 +756,7 @@ 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, + const enum color_transfer_func app_tf, struct dc_info_packet *infopacket) { /* SPD info packet for FreeSync 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..645793b924cf 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, + const enum color_transfer_func app_tf, struct dc_info_packet *infopacket);
void mod_freesync_build_vrr_params(struct mod_freesync *mod_freesync,
Thanks for the patch. We already have the fix queued: https://cgit.freedesktop.org/~agd5f/linux/commit/?h=drm-next-5.2-wip&id=...
Alex ________________________________ From: Arnd Bergmann arnd@arndb.de Sent: Thursday, March 7, 2019 5:34 AM To: Wentland, Harry; Li, Sun peng (Leo); Deucher, Alexander; Koenig, Christian; Zhou, David(ChunMing) Cc: Nick Desaulniers; Arnd Bergmann; David Airlie; Daniel Vetter; Koo, Anthony; Cyr, Aric; Tatla, Harmanprit; Chalmers, Kenneth; Kumarasamy, Sivapiriyan; Kees Cook; Bayan Zabihiyan; Cheng, Tony; amd-gfx@lists.freedesktop.org; dri-devel@lists.freedesktop.org; linux-kernel@vger.kernel.org Subject: [PATCH] drm/amd/display: avoid passing enum as NULL pointer
The mod_freesync_build_vrr_infopacket() function uses rather obscure calling conventions, where an enum is passed in through a pointer, and a NULL pointer is expected to behave the same way as the zero-value (TRANSFER_FUNC_UNKNOWN).
Trying to build this with clang results in a warning:
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:4601:3: error: expression which evaluates to zero treated as a null pointer constant of type 'const enum color_transfer_func *' [-Werror,-Wnon-literal-null-conversion]
Passing it by value instead of by reference makes the code simpler and more conventional but should not change the behavior at all.
Fixes: c2791297013e ("drm/amd/display: Add color bit info to freesync infoframe") Signed-off-by: Arnd Bergmann arnd@arndb.de --- drivers/gpu/drm/amd/display/modules/freesync/freesync.c | 7 +++---- drivers/gpu/drm/amd/display/modules/inc/mod_freesync.h | 2 +- 2 files changed, 4 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c index 94a84bc57c7a..6f32fe129880 100644 --- a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c +++ b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c @@ -724,7 +724,7 @@ static void build_vrr_infopacket_v1(enum signal_type signal,
static void build_vrr_infopacket_v2(enum signal_type signal, const struct mod_vrr_params *vrr, - const enum color_transfer_func *app_tf, + const enum color_transfer_func app_tf, struct dc_info_packet *infopacket) { unsigned int payload_size = 0; @@ -732,8 +732,7 @@ static void build_vrr_infopacket_v2(enum signal_type signal, build_vrr_infopacket_header_v2(signal, infopacket, &payload_size); build_vrr_infopacket_data(vrr, infopacket);
- if (app_tf != NULL) - build_vrr_infopacket_fs2_data(*app_tf, infopacket); + build_vrr_infopacket_fs2_data(app_tf, infopacket);
build_vrr_infopacket_checksum(&payload_size, infopacket);
@@ -757,7 +756,7 @@ 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, + const enum color_transfer_func app_tf, struct dc_info_packet *infopacket) { /* SPD info packet for FreeSync 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..645793b924cf 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, + const enum color_transfer_func app_tf, struct dc_info_packet *infopacket);
void mod_freesync_build_vrr_params(struct mod_freesync *mod_freesync, -- 2.20.0
On Thu, Mar 07, 2019 at 11:34:29AM +0100, Arnd Bergmann wrote:
The mod_freesync_build_vrr_infopacket() function uses rather obscure calling conventions, where an enum is passed in through a pointer, and a NULL pointer is expected to behave the same way as the zero-value (TRANSFER_FUNC_UNKNOWN).
Trying to build this with clang results in a warning:
drivers/gpu/drm/amd/amdgpu/../display/amdgpu_dm/amdgpu_dm.c:4601:3: error: expression which evaluates to zero treated as a null pointer constant of type 'const enum color_transfer_func *' [-Werror,-Wnon-literal-null-conversion]
Passing it by value instead of by reference makes the code simpler and more conventional but should not change the behavior at all.
Fixes: c2791297013e ("drm/amd/display: Add color bit info to freesync infoframe") Signed-off-by: Arnd Bergmann arnd@arndb.de
drivers/gpu/drm/amd/display/modules/freesync/freesync.c | 7 +++---- drivers/gpu/drm/amd/display/modules/inc/mod_freesync.h | 2 +- 2 files changed, 4 insertions(+), 5 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c index 94a84bc57c7a..6f32fe129880 100644 --- a/drivers/gpu/drm/amd/display/modules/freesync/freesync.c +++ b/drivers/gpu/drm/amd/display/modules/freesync/freesync.c @@ -724,7 +724,7 @@ static void build_vrr_infopacket_v1(enum signal_type signal,
static void build_vrr_infopacket_v2(enum signal_type signal, const struct mod_vrr_params *vrr,
const enum color_transfer_func *app_tf,
const enum color_transfer_func app_tf,{ unsigned int payload_size = 0; @@ -732,8 +732,7 @@ static void build_vrr_infopacket_v2(enum signal_type signal, build_vrr_infopacket_header_v2(signal, infopacket, &payload_size); build_vrr_infopacket_data(vrr, infopacket);
- if (app_tf != NULL)
build_vrr_infopacket_fs2_data(*app_tf, infopacket);
build_vrr_infopacket_fs2_data(app_tf, infopacket);
build_vrr_infopacket_checksum(&payload_size, infopacket);
@@ -757,7 +756,7 @@ 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,
const enum color_transfer_func app_tf,{ /* SPD info packet for FreeSync 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..645793b924cf 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,
const enum color_transfer_func app_tf,void mod_freesync_build_vrr_params(struct mod_freesync *mod_freesync,
2.20.0
Just as an FYI, I sent the same fix when the warning first hit which was recently accepted:
https://cgit.freedesktop.org/~agd5f/linux/commit/?id=672e78cab819ebe31e3b9b8...
Just waiting for it to hit mainline.
Cheers, Nathan
dri-devel@lists.freedesktop.org
-
Arnd Bergmann -
Deucher, Alexander -
Nathan Chancellor