[PATCH v2 20/28] drm/atomic_state_helper: Provide comparison macros

From: Maxime Ripard

Date: Thu Apr 23 2026 - 06:23:00 EST


In order to make the implementation of atomic_compare_state
easier and reduce the boilerplate, introduce a set of STATE_CHECK_*
macros to compare state field values depending on their type.

Signed-off-by: Maxime Ripard <mripard@xxxxxxxxxx>
---
drivers/gpu/drm/drm_atomic_sro_helper.c | 30 +++++
include/drm/drm_atomic_sro_helper.h | 219 ++++++++++++++++++++++++++++++++
2 files changed, 249 insertions(+)

diff --git a/drivers/gpu/drm/drm_atomic_sro_helper.c b/drivers/gpu/drm/drm_atomic_sro_helper.c
index 367d9bb7e442..b6411bfdba78 100644
--- a/drivers/gpu/drm/drm_atomic_sro_helper.c
+++ b/drivers/gpu/drm/drm_atomic_sro_helper.c
@@ -403,5 +403,35 @@ int drm_atomic_helper_sro_readout_state(struct drm_device *dev)
drm_atomic_sro_state_free(state);

return 0;
}
EXPORT_SYMBOL(drm_atomic_helper_sro_readout_state);
+
+/**
+ * drm_atomic_helper_print_state_mismatch - report a state comparison mismatch
+ * @p: printer to report through
+ * @name: human-readable name of the object (e.g. plane or CRTC name)
+ * @field: name of the mismatching field
+ * @format: printf-style format string describing the mismatch
+ *
+ * Helper used by atomic_sro_compare_state implementations and the
+ * STATE_CHECK_* macros to report a field-level mismatch between the
+ * committed state and the state read back from hardware.
+ */
+void __printf(4, 5)
+drm_atomic_helper_print_state_mismatch(struct drm_printer *p,
+ const char *name,
+ const char *field,
+ const char *format, ...)
+{
+ struct va_format vaf;
+ va_list args;
+
+ va_start(args, format);
+ vaf.fmt = format;
+ vaf.va = &args;
+
+ drm_printf(p, "%s configuration mismatch in %s %pV\n", name, field, &vaf);
+
+ va_end(args);
+}
+EXPORT_SYMBOL(drm_atomic_helper_print_state_mismatch);
diff --git a/include/drm/drm_atomic_sro_helper.h b/include/drm/drm_atomic_sro_helper.h
index a42ed8136a49..db5d62ac0db9 100644
--- a/include/drm/drm_atomic_sro_helper.h
+++ b/include/drm/drm_atomic_sro_helper.h
@@ -1,12 +1,15 @@
/* SPDX-License-Identifier: GPL-2.0-or-later */

#ifndef DRM_ATOMIC_SRO_HELPER_H_
#define DRM_ATOMIC_SRO_HELPER_H_

+#include <linux/string_choices.h>
+
struct drm_atomic_sro_state;
struct drm_device;
+struct drm_printer;

int
drm_atomic_helper_sro_readout_planes_state(struct drm_device *dev,
struct drm_atomic_sro_state *state);
int
@@ -23,6 +26,222 @@ drm_atomic_helper_sro_readout_private_objs_state(struct drm_device *dev,
struct drm_atomic_sro_state *state);
struct drm_atomic_sro_state *
drm_atomic_helper_sro_build_state(struct drm_device *dev);
int drm_atomic_helper_sro_readout_state(struct drm_device *dev);

+void __printf(4, 5)
+drm_atomic_helper_print_state_mismatch(struct drm_printer *p,
+ const char *name,
+ const char *field,
+ const char *format, ...);
+
+#define STATE_CHECK_BOOL(r, p, n, sa, sb, f) \
+ do { \
+ static_assert(__same_type(sa->f, sb->f), \
+ __stringify(f) " field types don't match"); \
+ static_assert(__same_type(sa->f, bool), \
+ __stringify(name) " is not a bool"); \
+ if (sa->f != sb->f) { \
+ drm_atomic_helper_print_state_mismatch(p, \
+ n, \
+ __stringify(f), \
+ "expected %s, got %s", \
+ str_yes_no(sa->f), \
+ str_yes_no(sb->f)); \
+ r = false; \
+ } \
+ } while (0)
+
+#define STATE_CHECK_DISPLAY_MODE(r, p, n, sa, sb, f) \
+ do { \
+ static_assert(__same_type(sa->f, sb->f), \
+ __stringify(f) " field types don't match"); \
+ static_assert(__same_type(sa->f, struct drm_display_mode), \
+ __stringify(name) " is not a drm_display_mode structure"); \
+ if (!drm_mode_equal(&sa->f, &sb->f)) { \
+ drm_atomic_helper_print_state_mismatch(p, \
+ n, \
+ __stringify(f), \
+ "expected " DRM_MODE_FMT ", got " DRM_MODE_FMT, \
+ DRM_MODE_ARG(&sa->f), \
+ DRM_MODE_ARG(&sb->f)); \
+ r = false; \
+ } \
+ } while (0)
+
+#define STATE_CHECK_INFOFRAME(r, p, n, sa, sb, f) \
+ do { \
+ static_assert(__same_type(sa->f, sb->f), \
+ __stringify(f) " field types don't match"); \
+ static_assert(__same_type(sa->f, union hdmi_infoframe), \
+ __stringify(name) " is not an hdmi_infoframe union"); \
+ if (memcmp(&sa->f, &sb->f, sizeof(union hdmi_infoframe))) { \
+ drm_atomic_helper_print_state_mismatch(p, \
+ n, \
+ __stringify(f), \
+ "infoframes don't match"); \
+ r = false; \
+ } \
+ } while (0)
+
+#define STATE_CHECK_FORMAT_INFO(r, p, n, sa, sb, f) \
+ do { \
+ static_assert(__same_type(sa->f, sb->f), \
+ __stringify(f) " field types don't match"); \
+ static_assert(__same_type(sa->f, const struct drm_format_info *), \
+ __stringify(name) " is not a drm_format_info pointer"); \
+ if (sa->f != sb->f) { \
+ drm_atomic_helper_print_state_mismatch(p, \
+ n, \
+ __stringify(f), \
+ "expected %p4cc, got %p4cc", \
+ &sa->f->format, \
+ &sb->f->format); \
+ r = false; \
+ } \
+ } while (0)
+
+#define STATE_CHECK_PROPERTY_BLOB(r, p, n, sa, sb, f) \
+ do { \
+ static_assert(__same_type(sa->f, sb->f), \
+ __stringify(f) " field types don't match"); \
+ static_assert(__same_type(sa->f, struct drm_property_blob *), \
+ __stringify(name) " is not a drm_property_blob pointer"); \
+ if (sa->f != sb->f && \
+ ((sa->f->length != sb->f->length) || \
+ memcmp(sa->f->data, sb->f->data, sa->f->length))) { \
+ drm_atomic_helper_print_state_mismatch(p, \
+ n, \
+ __stringify(f), \
+ "blobs don't match"); \
+ r = false; \
+ } \
+ } while (0)
+
+#define STATE_CHECK_PTR(r, p, n, sa, sb, f) \
+ do { \
+ static_assert(__same_type(sa->f, sb->f), \
+ __stringify(f) " field types don't match"); \
+ if (sa->f != sb->f) { \
+ drm_atomic_helper_print_state_mismatch(p, \
+ n, \
+ __stringify(f), \
+ "expected %p, got %p", \
+ sa->f, sb->f); \
+ r = false; \
+ } \
+ } while (0)
+
+#define STATE_CHECK_S32(r, p, n, sa, sb, f) \
+ do { \
+ static_assert(__same_type(sa->f, sb->f), \
+ __stringify(f) " field types don't match"); \
+ static_assert(__same_type(sa->f, (s32)0), \
+ __stringify(name) " is not an s32"); \
+ if (sa->f != sb->f) { \
+ drm_atomic_helper_print_state_mismatch(p, \
+ n, \
+ __stringify(f), \
+ "expected %u, got %u", \
+ sa->f, sb->f); \
+ r = false; \
+ } \
+ } while (0)
+
+#define STATE_CHECK_S32_X(r, p, n, sa, sb, f) \
+ do { \
+ static_assert(__same_type(sa->f, sb->f), \
+ __stringify(f) " field types don't match"); \
+ static_assert(__same_type(sa->f, (s32)0), \
+ __stringify(name) " is not an s32"); \
+ if (sa->f != sb->f) { \
+ drm_atomic_helper_print_state_mismatch(p, \
+ n, \
+ __stringify(f), \
+ "expected %x, got %x", \
+ sa->f, sb->f); \
+ r = false; \
+ } \
+ } while (0)
+
+#define STATE_CHECK_U16(r, p, n, sa, sb, f) \
+ do { \
+ static_assert(__same_type(sa->f, sb->f), \
+ __stringify(f) " field types don't match"); \
+ static_assert(__same_type(sa->f, (u16)0), \
+ __stringify(name) " is not a u16"); \
+ if (sa->f != sb->f) { \
+ drm_atomic_helper_print_state_mismatch(p, \
+ n, \
+ __stringify(f), \
+ "expected %u, got %u", \
+ sa->f, sb->f); \
+ r = false; \
+ } \
+ } while (0)
+
+#define STATE_CHECK_U32(r, p, n, sa, sb, f) \
+ do { \
+ static_assert(__same_type(sa->f, sb->f), \
+ __stringify(f) " field types don't match"); \
+ static_assert(__same_type(sa->f, (u32)0), \
+ __stringify(name) " is not a u32"); \
+ if (sa->f != sb->f) { \
+ drm_atomic_helper_print_state_mismatch(p, \
+ n, \
+ __stringify(f), \
+ "expected %u, got %u", \
+ sa->f, sb->f); \
+ r = false; \
+ } \
+ } while (0)
+
+#define STATE_CHECK_U32_16_16(r, p, n, sa, sb, f) \
+ do { \
+ static_assert(__same_type(sa->f, sb->f), \
+ __stringify(f) " field types don't match"); \
+ static_assert(__same_type(sa->f, (u32)0), \
+ __stringify(name) " is not a u32"); \
+ if (sa->f != sb->f) { \
+ drm_atomic_helper_print_state_mismatch(p, \
+ n, \
+ __stringify(f), \
+ "expected %d.%06u, got %d.%06u", \
+ sa->f >> 16, ((sa->f && 0xffff) * 15625) >> 10, \
+ sb->f >> 16, ((sb->f && 0xffff) * 15625) >> 10); \
+ r = false; \
+ } \
+ } while (0)
+
+#define STATE_CHECK_U32_X(r, p, n, sa, sb, f) \
+ do { \
+ static_assert(__same_type(sa->f, sb->f), \
+ __stringify(f) " field types don't match"); \
+ static_assert(__same_type(sa->f, (u32)0), \
+ __stringify(name) " is not a u32"); \
+ if (sa->f != sb->f) { \
+ drm_atomic_helper_print_state_mismatch(p, \
+ n, \
+ __stringify(f), \
+ "expected %08x, got %08x", \
+ sa->f, sb->f); \
+ r = false; \
+ } \
+ } while (0)
+
+#define STATE_CHECK_U64(r, p, n, sa, sb, f) \
+ do { \
+ static_assert(__same_type(sa->f, sb->f), \
+ __stringify(f) " field types don't match"); \
+ static_assert(__same_type(sa->f, (u64)0), \
+ __stringify(name) " is not a u64"); \
+ if (sa->f != sb->f) { \
+ drm_atomic_helper_print_state_mismatch(p, \
+ n, \
+ __stringify(f), \
+ "expected %llu, got %llu", \
+ sa->f, sb->f); \
+ r = false; \
+ } \
+ } while (0)
+
#endif /* DRM_ATOMIC_SRO_HELPER_H_ */

--
2.53.0