[PATCH] drm: enable warnings on unused static inlines

[Nathan Chancellor]

Hi Jani,

On Wed, Sep 04, 2024 at 03:38:19PM +0300, Jani Nikula wrote:
> We enable most W=1 warnings by default subsystem wide. Also enable
> warnings on unused static inlines when building with clang.
> 
> See also commit 6863f5643dd7 ("kbuild: allow Clang to find unused static
> inline functions for W=1 build").
> 
> Cc: Nathan Chancellor <nathan at kernel.org>
> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
> ---
>  drivers/gpu/drm/Makefile | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile
> index 784229d4504d..6bd2cdb08be7 100644
> --- a/drivers/gpu/drm/Makefile
> +++ b/drivers/gpu/drm/Makefile
> @@ -19,6 +19,9 @@ subdir-ccflags-y += $(call cc-option, -Wformat-overflow)
>  # FIXME: fix -Wformat-truncation warnings and uncomment
>  #subdir-ccflags-y += $(call cc-option, -Wformat-truncation)
>  subdir-ccflags-y += $(call cc-option, -Wstringop-truncation)
> +
> +subdir-ccflags-y += -DKBUILD_EXTRA_WARN1
> +
>  # The following turn off the warnings enabled by -Wextra
>  ifeq ($(findstring 2, $(KBUILD_EXTRA_WARN)),)
>  subdir-ccflags-y += -Wno-missing-field-initializers
> -- 
> 2.39.2
> 

I ran this through my test matrix and this is what it found (across
various configuration options, I can give specifics as necessary):

drivers/gpu/drm/bridge/synopsys/dw-hdmi-i2s-audio.c:30:18: warning: unused function 'hdmi_read' [-Wunused-function]
   30 | static inline u8 hdmi_read(struct dw_hdmi_i2s_audio_data *audio, int offset)
      |                  ^~~~~~~~~

drivers/gpu/drm/bridge/ti-sn65dsi86.c:1638:19: warning: unused function 'ti_sn_pwm_pin_request' [-Wunused-function]
 1638 | static inline int ti_sn_pwm_pin_request(struct ti_sn65dsi86 *pdata) { return 0; }
      |                   ^~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/bridge/ti-sn65dsi86.c:1639:20: warning: unused function 'ti_sn_pwm_pin_release' [-Wunused-function]
 1639 | static inline void ti_sn_pwm_pin_release(struct ti_sn65dsi86 *pdata) {}
      |                    ^~~~~~~~~~~~~~~~~~~~~

drivers/gpu/drm/drm_mm.c:152:1: warning: unused function 'drm_mm_interval_tree_insert' [-Wunused-function]
  152 | INTERVAL_TREE_DEFINE(struct drm_mm_node, rb,
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  153 |                      u64, __subtree_last,
      |                      ~~~~~~~~~~~~~~~~~~~~
  154 |                      START, LAST, static inline, drm_mm_interval_tree)
      |                      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/interval_tree_generic.h:38:15: note: expanded from macro 'INTERVAL_TREE_DEFINE'
   38 | ITSTATIC void ITPREFIX ## _insert(ITSTRUCT *node,                             \
      |               ^~~~~~~~~~~~~~~~~~~
<scratch space>:38:1: note: expanded from here
   38 | drm_mm_interval_tree_insert
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/drm_mm.c:152:1: warning: unused function 'drm_mm_interval_tree_iter_next' [-Wunused-function]
  152 | INTERVAL_TREE_DEFINE(struct drm_mm_node, rb,
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  153 |                      u64, __subtree_last,
      |                      ~~~~~~~~~~~~~~~~~~~~
  154 |                      START, LAST, static inline, drm_mm_interval_tree)
      |                      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/interval_tree_generic.h:151:33: note: expanded from macro 'INTERVAL_TREE_DEFINE'
  151 | ITSTATIC ITSTRUCT *                                                           \
      |                                                                               ^
  152 | ITPREFIX ## _iter_next(ITSTRUCT *node, ITTYPE start, ITTYPE last)             \
      | ~~~~~~~~~~~~~~~~~~~~~~
<scratch space>:50:1: note: expanded from here
   50 | drm_mm_interval_tree_iter_next
      | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/drm_mm.c:614:20: warning: function 'drm_mm_node_scanned_block' is not needed and will not be emitted [-Wunneeded-internal-declaration]
  614 | static inline bool drm_mm_node_scanned_block(const struct drm_mm_node *node)
      |                    ^~~~~~~~~~~~~~~~~~~~~~~~~

drivers/gpu/drm/i915/i915_sw_fence.c:97:20: error: unused function 'debug_fence_init_onstack' [-Werror,-Wunused-function]
   97 | static inline void debug_fence_init_onstack(struct i915_sw_fence *fence)
      |                    ^~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/i915/i915_sw_fence.c:118:20: error: unused function 'debug_fence_free' [-Werror,-Wunused-function]
  118 | static inline void debug_fence_free(struct i915_sw_fence *fence)
      |                    ^~~~~~~~~~~~~~~~

drivers/gpu/drm/imagination/pvr_drv.c:224:1: warning: unused function 'pvr_fw_version_packed' [-Wunused-function]
  224 | pvr_fw_version_packed(u32 major, u32 minor)
      | ^~~~~~~~~~~~~~~~~~~~~

drivers/gpu/drm/kmb/kmb_dsi.c:822:2: warning: unused function 'set_test_mode_src_osc_freq_target_low_bits' [-Wunused-function]
  822 |         set_test_mode_src_osc_freq_target_low_bits(struct kmb_dsi *kmb_dsi,
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/kmb/kmb_dsi.c:834:2: warning: unused function 'set_test_mode_src_osc_freq_target_hi_bits' [-Wunused-function]
  834 |         set_test_mode_src_osc_freq_target_hi_bits(struct kmb_dsi *kmb_dsi,
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

drivers/gpu/drm/meson/meson_dw_hdmi.c:276:20: warning: unused function 'dw_hdmi_dwc_write_bits' [-Wunused-function]
  276 | static inline void dw_hdmi_dwc_write_bits(struct meson_dw_hdmi *dw_hdmi,
      |                    ^~~~~~~~~~~~~~~~~~~~~~

drivers/gpu/drm/renesas/rcar-du/rcar_cmm.c:35:19: warning: unused function 'rcar_cmm_read' [-Wunused-function]
   35 | static inline int rcar_cmm_read(struct rcar_cmm *rcmm, u32 reg)
      |                   ^~~~~~~~~~~~~

drivers/gpu/drm/stm/ltdc.c:494:35: warning: unused function 'encoder_to_ltdc' [-Wunused-function]
  494 | static inline struct ltdc_device *encoder_to_ltdc(struct drm_encoder *enc)
      |                                   ^~~~~~~~~~~~~~~

Cheers,
Nathan