From 104cf8d905d96bf8ed33a033cd800c22eb90c4cc Mon Sep 17 00:00:00 2001
From: liquidraver <504870+liquidraver@users.noreply.github.com>
Date: Thu, 18 Jun 2026 07:33:41 +0200
Subject: [PATCH] fix smearing on eink after full update

---
 zephcore/helpers/ui/display.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/zephcore/helpers/ui/display.c b/zephcore/helpers/ui/display.c
index 44e9346..bf7da8c 100644
--- a/zephcore/helpers/ui/display.c
+++ b/zephcore/helpers/ui/display.c
@@ -529,6 +529,15 @@ void mc_display_finalize(void)
 		display_blanking_on(disp_dev);
 		cfb_framebuffer_finalize(disp_dev);
 		display_blanking_off(disp_dev);
+
+		/* Prime the partial-refresh reference frame.  After a full
+		 * refresh the SSD1681's "old frame" RAM is stale, so the first
+		 * partial diff produces a wrong delta and the partial waveform
+		 * smears static regions (e.g. the top bar).  One extra partial
+		 * finalize with the same content lets the controller record the
+		 * post-full-refresh state as its reference; it's a visual no-op
+		 * (zero-diff → no pixel transitions) but fixes subsequent diffs. */
+		cfb_framebuffer_finalize(disp_dev);
 		epd_partial_count = 0;
 	} else {
 		cfb_framebuffer_finalize(disp_dev);