drm/modeset: Handle tiled displays in pan_display_atomic.

Tiled displays have a different x/y offset to begin with. Instead of
attempting to remember this, just apply a delta instead.

This fixes the first tile being duplicated on other tiles when vt
switching.

Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20250116142825.3933-1-dev@lankhorst.se
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
Cc: <stable@vger.kernel.org>

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index c9008113111ba23d901bb0d48f27fea550e9778e..fb3614a7ba44bbd5e21d8c4547325a880506aa05 100644 (file)
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1354,14 +1354,14 @@ int drm_fb_helper_set_par(struct fb_info *info)
 }
 EXPORT_SYMBOL(drm_fb_helper_set_par);
 
-static void pan_set(struct drm_fb_helper *fb_helper, int x, int y)
+static void pan_set(struct drm_fb_helper *fb_helper, int dx, int dy)
 {
        struct drm_mode_set *mode_set;
 
        mutex_lock(&fb_helper->client.modeset_mutex);
        drm_client_for_each_modeset(mode_set, &fb_helper->client) {
-               mode_set->x = x;
-               mode_set->y = y;
+               mode_set->x += dx;
+               mode_set->y += dy;
        }
        mutex_unlock(&fb_helper->client.modeset_mutex);
 }
@@ -1370,16 +1370,18 @@ static int pan_display_atomic(struct fb_var_screeninfo *var,
                              struct fb_info *info)
 {
        struct drm_fb_helper *fb_helper = info->par;
-       int ret;
+       int ret, dx, dy;
 
-       pan_set(fb_helper, var->xoffset, var->yoffset);
+       dx = var->xoffset - info->var.xoffset;
+       dy = var->yoffset - info->var.yoffset;
+       pan_set(fb_helper, dx, dy);
 
        ret = drm_client_modeset_commit_locked(&fb_helper->client);
        if (!ret) {
                info->var.xoffset = var->xoffset;
                info->var.yoffset = var->yoffset;
        } else
-               pan_set(fb_helper, info->var.xoffset, info->var.yoffset);
+               pan_set(fb_helper, -dx, -dy);
 
        return ret;
 }