# --- T2-COPYRIGHT-BEGIN ---
# t2/package/*/linux/hotfix-ast-bigendian.patch
# Copyright (C) 2025 The T2 SDE Project
# SPDX-License-Identifier: GPL-2.0 or patched project license
# --- T2-COPYRIGHT-END ---

diff -urN /srv/t2/src.linux.sparc64.251130.134420.19457/linux-6.17/drivers/gpu/drm/ast/ast_mode.c linux-6.17/drivers/gpu/drm/ast/ast_mode.c
--- linux-6.17/drivers/gpu/drm/ast/ast_mode.c	2025-09-28 23:39:22.000000000 +0200
+++ linux-6.17/drivers/gpu/drm/ast/ast_mode.c	2025-11-30 13:44:02.286167417 +0100
@@ -708,6 +708,20 @@
 	ast_set_dclk_reg(ast, adjusted_mode, vmode);
 	ast_set_crtthd_reg(ast);
 	ast_set_sync_reg(ast, adjusted_mode, vmode);
+
+#ifdef __BIG_ENDIAN
+	/* Big-endian byte-swapping */
+	switch (ast_crtc_state->format->format) {
+	case DRM_FORMAT_RGB565:
+		ast_set_index_reg_mask(ast, AST_IO_VGACRI, AST_IO_VGACRA2, 0x3f, 0x40);
+		break;
+	case DRM_FORMAT_XRGB8888:
+		ast_set_index_reg_mask(ast, AST_IO_VGACRI, AST_IO_VGACRA2, 0x3f, 0x80);
+		break;
+	default:
+		break;
+	}
+#endif
 }
 
 static int ast_crtc_helper_atomic_check(struct drm_crtc *crtc,
diff -urN /srv/t2/src.linux.sparc64.251130.134420.19457/linux-6.17/drivers/gpu/drm/ast/ast_reg.h linux-6.17/drivers/gpu/drm/ast/ast_reg.h
--- linux-6.17/drivers/gpu/drm/ast/ast_reg.h	2025-09-28 23:39:22.000000000 +0200
+++ linux-6.17/drivers/gpu/drm/ast/ast_reg.h	2025-11-30 13:15:34.812579282 +0100
@@ -74,4 +74,10 @@
 #define AST_IO_VGAIR1_R			(0x5A)
 #define AST_IO_VGAIR1_VREFRESH		BIT(3)
 
+/*
+ * PCI Control
+ */
+
+#define AST_IO_VGACRA2			(0xA2) /* PCI control & big-endian */
+
 #endif