drm/i915: Use container_of_const() for states

commit 64f6a5d1922b ("container_of: add container_of_const()
that preserves const-ness of the pointer") is nice. Let's use
it so that we don't accidentally cast away the const from our
state pointers.

The only thing I don't particularly like about container_of_const()
is that it still accepts void* in addition to the proper pointer
types, but that's how most other things in C work anyway so I
guess we can live with it.

And while at it rename the macro arguments to be a bit more
descriptive than just 'x'.

TODO: maybe convert *all* container_of() uses to container_of_const()?

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240307151810.24208-4-ville.syrjala@linux.intel.com
Reviewed-by: Jani Nikula <jani.nikula@intel.com>

1 files changed, 2 insertions, 3 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_pmdemand.h b/drivers/gpu/drm/i915/display/intel_pmdemand.h
index 2941a1a18b72..128fd61f8f14 100644
--- a/drivers/gpu/drm/i915/display/intel_pmdemand.h
+++ b/drivers/gpu/drm/i915/display/intel_pmdemand.h
@@ -43,9 +43,8 @@ struct intel_pmdemand_state {
 	struct pmdemand_params params;
 };
 
-#define to_intel_pmdemand_state(x) container_of((x), \
-						struct intel_pmdemand_state, \
-						base)
+#define to_intel_pmdemand_state(global_state) \
+	container_of_const((global_state), struct intel_pmdemand_state, base)
 
 void intel_pmdemand_init_early(struct drm_i915_private *i915);
 int intel_pmdemand_init(struct drm_i915_private *i915);