[RFC v3 07/12] drm/modes: Add drm_umode_equal()

["Noralf Trønnes" <noralf@tronnes.org>]

Add a way to check if userspace modes are equal. Useful for in-kernel
clients. Also export drm_mode_convert_umode().

Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
---
 drivers/gpu/drm/drm_modes.c | 50 +++++++++++++++++++++++++++++++++++++++++++++
 include/drm/drm_modes.h     |  2 ++
 2 files changed, 52 insertions(+)

diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index 5a8033fda4e3..0e39164f15aa 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -1631,6 +1631,56 @@ int drm_mode_convert_umode(struct drm_device *dev,
 out:
 	return ret;
 }
+EXPORT_SYMBOL(drm_mode_convert_umode);
+
+/**
+ * drm_umode_equal - test modeinfo modes for equality
+ * @mode1: first mode
+ * @mode2: second mode
+ *
+ * Check to see if @mode1 and @mode2 are equivalent.
+ *
+ * Returns:
+ * True if the modes are equal, false otherwise.
+ */
+bool drm_umode_equal(const struct drm_mode_modeinfo *mode1,
+		     const struct drm_mode_modeinfo *mode2)
+{
+	if (!mode1 && !mode2)
+		return true;
+
+	if (!mode1 || !mode2)
+		return false;
+
+	/* do clock check convert to PICOS so fb modes get matched the same */
+	if (mode1->clock && mode2->clock) {
+		if (KHZ2PICOS(mode1->clock) != KHZ2PICOS(mode2->clock))
+			return false;
+	} else if (mode1->clock != mode2->clock) {
+		return false;
+	}
+
+	if ((mode1->flags & DRM_MODE_FLAG_3D_MASK) !=
+	    (mode2->flags & DRM_MODE_FLAG_3D_MASK))
+		return false;
+
+	if (mode1->hdisplay == mode2->hdisplay &&
+	    mode1->hsync_start == mode2->hsync_start &&
+	    mode1->hsync_end == mode2->hsync_end &&
+	    mode1->htotal == mode2->htotal &&
+	    mode1->hskew == mode2->hskew &&
+	    mode1->vdisplay == mode2->vdisplay &&
+	    mode1->vsync_start == mode2->vsync_start &&
+	    mode1->vsync_end == mode2->vsync_end &&
+	    mode1->vtotal == mode2->vtotal &&
+	    mode1->vscan == mode2->vscan &&
+	    (mode1->flags & ~DRM_MODE_FLAG_3D_MASK) ==
+	     (mode2->flags & ~DRM_MODE_FLAG_3D_MASK))
+		return true;
+
+	return false;
+}
+EXPORT_SYMBOL(drm_umode_equal);
 
 /**
  * drm_mode_is_420_only - if a given videomode can be only supported in YCBCR420
diff --git a/include/drm/drm_modes.h b/include/drm/drm_modes.h
index 0d310beae6af..05e73ca4f2ae 100644
--- a/include/drm/drm_modes.h
+++ b/include/drm/drm_modes.h
@@ -447,6 +447,8 @@ void drm_mode_convert_to_umode(struct drm_mode_modeinfo *out,
 int drm_mode_convert_umode(struct drm_device *dev,
 			   struct drm_display_mode *out,
 			   const struct drm_mode_modeinfo *in);
+bool drm_umode_equal(const struct drm_mode_modeinfo *mode1,
+		     const struct drm_mode_modeinfo *mode2);
 void drm_mode_probed_add(struct drm_connector *connector, struct drm_display_mode *mode);
 void drm_mode_debug_printmodeline(const struct drm_display_mode *mode);
 bool drm_mode_is_420_only(const struct drm_display_info *display,
-- 
2.15.1

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