# --- T2-COPYRIGHT-BEGIN ---
# t2/package/*/xf86-video-cirrus/hotfix-laguna-pitch.patch
# Copyright (C) 2026 The T2 SDE Project
# SPDX-License-Identifier: GPL-2.0 or patched project license
# --- T2-COPYRIGHT-END ---

Fix line pitch handling, e.g. 1400x @ 16 bit resulted in an unsupported
pitch breaking xaa.

--- xf86-video-cirrus-1.6.0/src/lg_driver.c.orig	2022-07-11 01:49:51.000000000 +0200
+++ xf86-video-cirrus-1.6.0/src/lg_driver.c	2026-07-12 19:39:20.036994195 +0200
@@ -928,11 +928,51 @@
                             pScrn->display->virtualY,
                             pCir->FbMapSize, LOOKUP_BEST_REFRESH);
 
+    if (i == -1) {
+        LgFreeRec(pScrn);
+        return FALSE;
+    }
+
     pCir->chip.lg->lineDataIndex =
                                 LgFindLineData(pScrn->displayWidth,
                                                 pScrn->bitsPerPixel);
 
-    if (i == -1) {
+    if (pCir->chip.lg->lineDataIndex < 0) {
+        xf86DrvMsg(pScrn->scrnIndex, X_ERROR,
+                    "No tile pitch available for a display width of "
+                    "%d pixels at %d bpp\n",
+                    pScrn->displayWidth, pScrn->bitsPerPixel);
+        LgFreeRec(pScrn);
+        return FALSE;
+    }
+
+    /*
+     * The chip can only scan out (and blit to) a line whose pitch is one
+     * of the tiled pitches in LgLineData[], and LgFindLineData() rounds
+     * up to the next one of those.  xf86ValidateModes() only picks a
+     * pitch out of LgLinePitches[] when a virtual size is configured;
+     * otherwise it just rounds the width up to the pitch increment, which
+     * can leave displayWidth *smaller* than the pitch we are about to
+     * programme (e.g. 1400 -> 1408 pixels = 2816 bytes, while the chip
+     * gets the next tiled pitch up, 3328 bytes).  fb, the BitBLT engine
+     * and the CRTC all have to agree, so widen displayWidth to the pitch
+     * the hardware will actually use.
+     */
+    pScrn->displayWidth = LgLineData[pCir->chip.lg->lineDataIndex].pitch /
+                            (pScrn->bitsPerPixel >> 3);
+
+    /*
+     * Widening the pitch costs memory, so make sure we did not just grow
+     * the frame buffer beyond the end of video RAM.
+     */
+    if (pScrn->displayWidth * pScrn->virtualY * (pScrn->bitsPerPixel >> 3) >
+            pCir->FbMapSize) {
+        xf86DrvMsg(pScrn->scrnIndex, X_ERROR,
+                    "Virtual size %dx%d at %d bpp needs a line pitch of "
+                    "%d pixels, which does not fit in %d kByte of video "
+                    "RAM\n",
+                    pScrn->virtualX, pScrn->virtualY, pScrn->bitsPerPixel,
+                    pScrn->displayWidth, pScrn->videoRam);
         LgFreeRec(pScrn);
         return FALSE;
     }