drm/i915: Mark expected switch fall-throughs

In preparation to enabling -Wimplicit-fallthrough, mark switch
cases where we are expecting to fall through.

This patch fixes the following warnings:

drivers/gpu/drm/i915/gem/i915_gem_mman.c: In function ‘i915_gem_fault’:
drivers/gpu/drm/i915/gem/i915_gem_mman.c:342:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (!i915_terminally_wedged(i915))
      ^
drivers/gpu/drm/i915/gem/i915_gem_mman.c:345:2: note: here
  case -EAGAIN:
  ^~~~

drivers/gpu/drm/i915/gem/i915_gem_pages.c: In function ‘i915_gem_object_map’:
./include/linux/compiler.h:78:22: warning: this statement may fall through [-Wimplicit-fallthrough=]
 # define unlikely(x) __builtin_expect(!!(x), 0)
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~
./include/asm-generic/bug.h:136:2: note: in expansion of macro ‘unlikely’
  unlikely(__ret_warn_on);     \
  ^~~~~~~~
drivers/gpu/drm/i915/i915_utils.h:49:25: note: in expansion of macro ‘WARN’
 #define MISSING_CASE(x) WARN(1, "Missing case (%s == %ld)\n", \
                         ^~~~
drivers/gpu/drm/i915/gem/i915_gem_pages.c:270:3: note: in expansion of macro ‘MISSING_CASE’
   MISSING_CASE(type);
   ^~~~~~~~~~~~
drivers/gpu/drm/i915/gem/i915_gem_pages.c:272:2: note: here
  case I915_MAP_WB:
  ^~~~

drivers/gpu/drm/i915/i915_gpu_error.c: In function ‘error_record_engine_registers’:
./include/linux/compiler.h:78:22: warning: this statement may fall through [-Wimplicit-fallthrough=]
 # define unlikely(x) __builtin_expect(!!(x), 0)
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~
./include/asm-generic/bug.h:136:2: note: in expansion of macro ‘unlikely’
  unlikely(__ret_warn_on);     \
  ^~~~~~~~
drivers/gpu/drm/i915/i915_utils.h:49:25: note: in expansion of macro ‘WARN’
 #define MISSING_CASE(x) WARN(1, "Missing case (%s == %ld)\n", \
                         ^~~~
drivers/gpu/drm/i915/i915_gpu_error.c:1196:5: note: in expansion of macro ‘MISSING_CASE’
     MISSING_CASE(engine->id);
     ^~~~~~~~~~~~
drivers/gpu/drm/i915/i915_gpu_error.c:1197:4: note: here
    case RCS0:
    ^~~~

drivers/gpu/drm/i915/display/intel_dp.c: In function ‘intel_dp_get_fia_supported_lane_count’:
./include/linux/compiler.h:78:22: warning: this statement may fall through [-Wimplicit-fallthrough=]
 # define unlikely(x) __builtin_expect(!!(x), 0)
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~
./include/asm-generic/bug.h:136:2: note: in expansion of macro ‘unlikely’
  unlikely(__ret_warn_on);     \
  ^~~~~~~~
drivers/gpu/drm/i915/i915_utils.h:49:25: note: in expansion of macro ‘WARN’
 #define MISSING_CASE(x) WARN(1, "Missing case (%s == %ld)\n", \
                         ^~~~
drivers/gpu/drm/i915/display/intel_dp.c:233:3: note: in expansion of macro ‘MISSING_CASE’
   MISSING_CASE(lane_info);
   ^~~~~~~~~~~~
drivers/gpu/drm/i915/display/intel_dp.c:234:2: note: here
  case 1:
  ^~~~

drivers/gpu/drm/i915/display/intel_display.c: In function ‘check_digital_port_conflicts’:
  CC [M]  drivers/gpu/drm/nouveau/nvkm/engine/disp/cursgv100.o
drivers/gpu/drm/i915/display/intel_display.c:12043:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
    if (WARN_ON(!HAS_DDI(to_i915(dev))))
       ^
drivers/gpu/drm/i915/display/intel_display.c:12046:3: note: here
   case INTEL_OUTPUT_DP:
   ^~~~

Also, notice that the Makefile is modified to stop ignoring
fall-through warnings. The -Wimplicit-fallthrough option
will be enabled globally in v5.3.

Warning level 3 was used: -Wimplicit-fallthrough=3

This patch is part of the ongoing efforts to enable
-Wimplicit-fallthrough.

Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 91355c2..8cace65 100644 (file)
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -16,7 +16,6 @@ subdir-ccflags-y := -Wall -Wextra
 subdir-ccflags-y += $(call cc-disable-warning, unused-parameter)
 subdir-ccflags-y += $(call cc-disable-warning, type-limits)
 subdir-ccflags-y += $(call cc-disable-warning, missing-field-initializers)
-subdir-ccflags-y += $(call cc-disable-warning, implicit-fallthrough)
 subdir-ccflags-y += $(call cc-disable-warning, unused-but-set-variable)
 # clang warnings
 subdir-ccflags-y += $(call cc-disable-warning, sign-compare)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 8592a7d..30b97de 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -12042,7 +12042,7 @@ static bool check_digital_port_conflicts(struct intel_atomic_state *state)
                case INTEL_OUTPUT_DDI:
                        if (WARN_ON(!HAS_DDI(to_i915(dev))))
                                break;
-                       /* else: fall through */
+                       /* else, fall through */
                case INTEL_OUTPUT_DP:
                case INTEL_OUTPUT_HDMI:
                case INTEL_OUTPUT_EDP:

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 4336df4..d0fc348 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -231,6 +231,7 @@ static int intel_dp_get_fia_supported_lane_count(struct intel_dp *intel_dp)
        switch (lane_info) {
        default:
                MISSING_CASE(lane_info);
+               /* fall through */
        case 1:
        case 2:
        case 4:

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
index 391621e..39a6619 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
@@ -341,7 +341,7 @@ err:
                 */
                if (!i915_terminally_wedged(i915))
                        return VM_FAULT_SIGBUS;
-               /* else: fall through */
+               /* else, fall through */
        case -EAGAIN:
                /*
                 * EAGAIN means the gpu is hung and we'll wait for the error

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pages.c b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
index b36ad26..65eb430 100644 (file)
--- a/drivers/gpu/drm/i915/gem/i915_gem_pages.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_pages.c
@@ -268,7 +268,7 @@ static void *i915_gem_object_map(const struct drm_i915_gem_object *obj,
        switch (type) {
        default:
                MISSING_CASE(type);
-               /* fallthrough to use PAGE_KERNEL anyway */
+               /* fallthrough - to use PAGE_KERNEL anyway */
        case I915_MAP_WB:
                pgprot = PAGE_KERNEL;
                break;

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index b7e9fdd..41a511d 100644 (file)
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -1194,6 +1194,7 @@ static void error_record_engine_registers(struct i915_gpu_state *error,
                        switch (engine->id) {
                        default:
                                MISSING_CASE(engine->id);
+                               /* fall through */
                        case RCS0:
                                mmio = RENDER_HWS_PGA_GEN7;
                                break;