VX900 (and all HI-engine chips): fix two-color hardware cursor showing garbage.

The Hardware Icon (HI) engine used by CX700 and later parts is ARGB-only and
has no two-color cursor mode.  For those chips iga_crtc_load_cursor_image()
(the X server's two-color / core-cursor path) could not feed the engine, so a
two-color cursor left it fetching stale video RAM at the cursor position -- the
cursor appeared at the correct location but showing random data.

Withhold the load_cursor_image callback for HI-engine chips (only the CLE266 /
KM400 dedicated two-color engine keeps it).  The X server then expands two-color
cursors to ARGB itself and drives them through iga_crtc_load_cursor_argb(),
re-converting on every color and image change, which also avoids foreground /
background getting swapped when alternating cursors.  Full-color ARGB cursors
were already handled by iga_crtc_load_cursor_argb() and are unchanged.

Signed-off-by: René Rebe <rene@exactco.de>

--- xf86-video-openchrome.git/src/via_ums.h	2026-07-20 18:19:18.468012621 +0200
+++ xf86-video-openchrome.git.new/src/via_ums.h	2026-07-20 18:19:18.468454011 +0200
@@ -1620,8 +1620,8 @@ void viaIGA2SetDisplayRegister(ScrnInfoP
 void viaIGA2Save(ScrnInfoPtr pScrn);
 void viaIGA2Restore(ScrnInfoPtr pScrn);
 void ViaShadowCRTCSetMode(ScrnInfoPtr pScrn, DisplayModePtr mode);
-extern const xf86CrtcFuncsRec iga1_crtc_funcs;
-extern const xf86CrtcFuncsRec iga2_crtc_funcs;
+extern xf86CrtcFuncsRec iga1_crtc_funcs;
+extern xf86CrtcFuncsRec iga2_crtc_funcs;
 
 /* via_analog.c */
 void viaAnalogProbe(ScrnInfoPtr pScrn);
--- xf86-video-openchrome.git/src/via_ums.c	2026-07-20 18:19:18.465692915 +0200
+++ xf86-video-openchrome.git.new/src/via_ums.c	2026-07-20 18:19:18.466214438 +0200
@@ -1428,6 +1428,19 @@ viaUMSCrtcInit(ScrnInfoPtr pScrn)
     pScrn->clockRanges = clockRanges;
 
     /*
+     * The Hardware Icon (HI) engine used by CX700 and later chipsets is
+     * ARGB-only.  Withhold the two-color (load_cursor_image) callback for
+     * those parts so the X server expands two-color cursors to ARGB itself and
+     * drives them through load_cursor_argb; otherwise the two-color path has no
+     * way to feed the HI engine and it scans out stale video RAM.  Only the
+     * CLE266 / KM400 dedicated two-color engine keeps the callback.
+     */
+    if ((pVia->Chipset != VIA_CLE266) && (pVia->Chipset != VIA_KM400)) {
+        iga1_crtc_funcs.load_cursor_image = NULL;
+        iga2_crtc_funcs.load_cursor_image = NULL;
+    }
+
+    /*
      * Now handle the outputs
      */
     iga1_rec = (drmmode_crtc_private_ptr) xnfcalloc(sizeof(drmmode_crtc_private_rec), 1);
--- xf86-video-openchrome.git/src/via_display.c	2026-07-20 18:19:18.462974280 +0200
+++ xf86-video-openchrome.git.new/src/via_display.c	2026-07-20 18:19:18.463487154 +0200
@@ -3421,35 +3421,18 @@ iga_crtc_set_cursor_colors(xf86CrtcPtr c
 {
     ScrnInfoPtr pScrn = crtc->scrn;
     VIAPtr pVia = VIAPTR(pScrn);
-    drmmode_crtc_private_ptr iga = crtc->driver_private;
-    xf86CrtcConfigPtr xf86_config = XF86_CRTC_CONFIG_PTR(pScrn);
 
+    /*
+     * Only the CLE266 / KM400 dedicated two-color cursor engine consumes
+     * separate foreground / background colors.  HI-engine chips do not
+     * register load_cursor_image (see iga1_crtc_funcs / iga2_crtc_funcs), so
+     * the X server expands two-color cursors to ARGB itself and never calls
+     * this for them.
+     */
     if (viaCursorOldEngine(pVia)) {
-        /* Two-color cursor: foreground / background come from registers. */
         VIASETREG(VIA_REG_CURSOR_BG, bg);
         VIASETREG(VIA_REG_CURSOR_FG, fg);
-        return;
-    }
-
-    if (xf86_config->cursor_fg)
-        return;
-
-    /*
-     * Don't recolour the image if we don't have to.
-     */
-    if ((fg == xf86_config->cursor_fg) &&
-        (bg == xf86_config->cursor_bg)) {
-        return;
     }
-
-    if (!iga->index) {
-        viaIGA1DisplayHI(pScrn, FALSE);
-    } else {
-        viaIGA2DisplayHI(pScrn, FALSE);
-    }
-
-    xf86_config->cursor_fg = fg;
-    xf86_config->cursor_bg = bg;
 }
 
 static void
@@ -3555,11 +3538,13 @@ iga_crtc_load_cursor_argb(xf86CrtcPtr cr
 }
 
 /*
- * Upload a two-color cursor image for the CLE266 / KM400 UniChrome cursor
- * engine.  The X server hands us a 32x32 two-plane (AND source + mask) image
- * (256 bytes) which is copied verbatim into video RAM, and the cursor engine
- * is pointed at it via VIA_REG_CURSOR_MODE (byte offset in the low address
- * bits, cursor control in bits [1:0]).
+ * Upload a two-color (source/mask) cursor image for the CLE266 / KM400
+ * UniChrome dedicated 32x32 two-color cursor engine.
+ *
+ * All later parts drive the cursor through the ARGB-only Hardware Icon (HI)
+ * engine, which has no two-color mode.  Those chips therefore do NOT register
+ * this callback (see iga1_crtc_funcs / iga2_crtc_funcs); the X server expands
+ * their two-color cursors to ARGB via iga_crtc_load_cursor_argb() instead.
  */
 static void
 iga_crtc_load_cursor_image(xf86CrtcPtr crtc, CARD8 *image)
@@ -3603,7 +3588,7 @@ iga_crtc_destroy(xf86CrtcPtr crtc)
         free(crtc->driver_private);
 }
 
-const xf86CrtcFuncsRec iga1_crtc_funcs = {
+xf86CrtcFuncsRec iga1_crtc_funcs = {
     .dpms                   = iga1_crtc_dpms,
     .save                   = iga1_crtc_save,
     .restore                = iga1_crtc_restore,
@@ -3917,7 +3902,7 @@ iga2_crtc_shadow_destroy(xf86CrtcPtr crt
 {
 }
 
-const xf86CrtcFuncsRec iga2_crtc_funcs = {
+xf86CrtcFuncsRec iga2_crtc_funcs = {
     .dpms                   = iga2_crtc_dpms,
     .save                   = iga2_crtc_save,
     .restore                = iga2_crtc_restore,