Use two HW cursor buffers per CRTC

Switch to the other buffer when xf86_config->cursor changes. Avoids
these issues possible when re-using the same buffer:

* The HW may intermittently display a mix of the old and new cursor
  images.
* If the hotspot changes, the HW may intermittently display the new
  cursor image at the location corresponding to the old image's hotspot.

Bugzilla: https://bugs.freedesktop.org/108832
(Ported from amdgpu commit 0d60233d26ec70d4e1faa343b438e33829c6d5e4)

3 files changed, 37 insertions, 20 deletions

diff --git a/src/drmmode_display.c b/src/drmmode_display.c
index bec309e5..d433e061 100644
--- a/src/drmmode_display.c
+++ b/src/drmmode_display.c
@@ -1122,13 +1122,18 @@ drmmode_load_cursor_argb (xf86CrtcPtr crtc, CARD32 *image)
 	ScrnInfoPtr pScrn = crtc->scrn;
 	RADEONInfoPtr info = RADEONPTR(pScrn);
 	drmmode_crtc_private_ptr drmmode_crtc = crtc->driver_private;
+	unsigned id = drmmode_crtc->cursor_id;
 	Bool premultiplied = TRUE;
 	Bool apply_gamma = TRUE;
 	uint32_t argb;
 	uint32_t *ptr;
 
+	if (drmmode_crtc->cursor &&
+	    XF86_CRTC_CONFIG_PTR(pScrn)->cursor != drmmode_crtc->cursor)
+		id ^= 1;
+
 	/* cursor should be mapped already */
-	ptr = (uint32_t *)(drmmode_crtc->cursor_bo->ptr);
+	ptr = (uint32_t *)(drmmode_crtc->cursor_bo[id]->ptr);
 
 	if (crtc->scrn->depth != 24 && crtc->scrn->depth != 32)
 		apply_gamma = FALSE;
@@ -1170,6 +1175,11 @@ retry:
 			ptr[i] = cpu_to_le32(argb);
 		}
 	}
+
+	if (id != drmmode_crtc->cursor_id) {
+		drmmode_crtc->cursor_id = id;
+		crtc->funcs->show_cursor(crtc);
+	}
 }
 
 #if XORG_VERSION_CURRENT >= XORG_VERSION_NUMERIC(1,15,99,903,0)
@@ -1195,7 +1205,7 @@ drmmode_hide_cursor (xf86CrtcPtr crtc)
 
 	drmModeSetCursor(pRADEONEnt->fd, drmmode_crtc->mode_crtc->crtc_id, 0,
 			 info->cursor_w, info->cursor_h);
-
+	drmmode_crtc->cursor = NULL;
 }
 
 static void
@@ -1212,9 +1222,11 @@ drmmode_show_cursor (xf86CrtcPtr crtc)
 	static Bool use_set_cursor2 = TRUE;
 	struct drm_mode_cursor2 arg;
 
+	drmmode_crtc->cursor = xf86_config->cursor;
+
 	memset(&arg, 0, sizeof(arg));
 
-	arg.handle = drmmode_crtc->cursor_bo->handle;
+	arg.handle = drmmode_crtc->cursor_bo[drmmode_crtc->cursor_id]->handle;
 	arg.flags = DRM_MODE_CURSOR_BO;
 	arg.crtc_id = drmmode_crtc->mode_crtc->crtc_id;
 	arg.width = info->cursor_w;
diff --git a/src/drmmode_display.h b/src/drmmode_display.h
index 49893ab0..2c2c3d57 100644
--- a/src/drmmode_display.h
+++ b/src/drmmode_display.h
@@ -88,11 +88,14 @@ typedef struct {
     drmModeCrtcPtr mode_crtc;
     int hw_id;
 
+    CursorPtr cursor;
     int cursor_x;
     int cursor_y;
     int cursor_xhot;
     int cursor_yhot;
-    struct radeon_bo *cursor_bo;
+    unsigned cursor_id;
+    struct radeon_bo *cursor_bo[2];
+
     struct drmmode_scanout rotate;
     struct drmmode_scanout scanout[2];
     DamagePtr scanout_damage;
diff --git a/src/radeon_kms.c b/src/radeon_kms.c
index 27a02109..bb6885fb 100644
--- a/src/radeon_kms.c
+++ b/src/radeon_kms.c
@@ -2755,27 +2755,29 @@ static Bool radeon_setup_kernel_mem(ScreenPtr pScreen)
 
     {
 	int cursor_size;
-	int c;
+	int c, i;
 
 	cursor_size = info->cursor_w * info->cursor_h * 4;
 	cursor_size = RADEON_ALIGN(cursor_size, RADEON_GPU_PAGE_SIZE);
 	for (c = 0; c < xf86_config->num_crtc; c++) {
 	    drmmode_crtc_private_ptr drmmode_crtc = xf86_config->crtc[c]->driver_private;
 
-	    if (!drmmode_crtc->cursor_bo) {
-		drmmode_crtc->cursor_bo = radeon_bo_open(info->bufmgr, 0,
-							 cursor_size, 0,
-							 RADEON_GEM_DOMAIN_VRAM, 0);
-		if (!(drmmode_crtc->cursor_bo)) {
-                    ErrorF("Failed to allocate cursor buffer memory\n");
-                    return FALSE;
-                }
-
-		if (radeon_bo_map(drmmode_crtc->cursor_bo, 1)) {
-                    ErrorF("Failed to map cursor buffer memory\n");
-                }
-            }
-        }
+	    for (i = 0; i < 2; i++) {
+		if (!drmmode_crtc->cursor_bo[i]) {
+		    drmmode_crtc->cursor_bo[i] =
+			radeon_bo_open(info->bufmgr, 0, cursor_size, 0,
+				       RADEON_GEM_DOMAIN_VRAM, 0);
+
+		    if (!(drmmode_crtc->cursor_bo[i])) {
+			ErrorF("Failed to allocate cursor buffer memory\n");
+			return FALSE;
+		    }
+
+		    if (radeon_bo_map(drmmode_crtc->cursor_bo[i], 1))
+			ErrorF("Failed to map cursor buffer memory\n");
+		}
+	    }
+	}
     }
 
     if (!info->front_buffer) {
@@ -2841,7 +2843,7 @@ void radeon_kms_update_vram_limit(ScrnInfoPtr pScrn, uint32_t new_fb_size)
     for (c = 0; c < xf86_config->num_crtc; c++) {
 	drmmode_crtc_private_ptr drmmode_crtc = xf86_config->crtc[c]->driver_private;
 
-	if (drmmode_crtc->cursor_bo)
+	if (drmmode_crtc->cursor_bo[0])
 	    new_fb_size += (64 * 4 * 64);
     }