drm/fb-helper: Set flag in struct drm_fb_helper for leaking physical addresses

Uncouple the parameter drm_leak_fbdev_smem from the implementation by
setting a flag in struct drm_fb_helper. This will help to move the
generic fbdev emulation into its own source file, while keeping the
parameter in drm_fb_helper.c. No functional changes.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20221103151446.2638-21-tzimmermann@suse.de

drivers/gpu/drm/drm_fb_helper.c

@@ -74,7 +74,7 @@ MODULE_PARM_DESC(drm_fbdev_overalloc,
  * considered as a broken and legacy behaviour from a modern fbdev device.
  */
 #if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
-static bool drm_leak_fbdev_smem = false;
+static bool drm_leak_fbdev_smem;
 module_param_unsafe(drm_leak_fbdev_smem, bool, 0600);
 MODULE_PARM_DESC(drm_leak_fbdev_smem,
 		 "Allow unsafe leaking fbdev physical smem address [default=false]");
@@ -1968,6 +1968,10 @@ static int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
 		sizes.surface_height = config->max_height;
 	}
 
+#if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
+	fb_helper->hint_leak_smem_start = drm_leak_fbdev_smem;
+#endif
+
 	/* push down into drivers */
 	ret = (*fb_helper->funcs->fb_probe)(fb_helper, &sizes);
 	if (ret < 0)
@@ -2165,7 +2169,7 @@ __drm_fb_helper_initial_config_and_unlock(struct drm_fb_helper *fb_helper,
 	info->var.pixclock = 0;
 	/* Shamelessly allow physical address leaking to userspace */
 #if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
-	if (!drm_leak_fbdev_smem)
+	if (!fb_helper->hint_leak_smem_start)
 #endif
 		/* don't leak any physical addresses to userspace */
 		info->flags |= FBINFO_HIDE_SMEM_START;
@@ -2564,7 +2568,7 @@ static int drm_fb_helper_generic_probe(struct drm_fb_helper *fb_helper,
 		 * case.
 		 */
 #if IS_ENABLED(CONFIG_DRM_FBDEV_LEAK_PHYS_SMEM)
-		if (drm_leak_fbdev_smem && fbi->fix.smem_start == 0 &&
+		if (fb_helper->hint_leak_smem_start && fbi->fix.smem_start == 0 &&
 		    !drm_WARN_ON_ONCE(dev, map.is_iomem))
 			fbi->fix.smem_start =
 				page_to_phys(virt_to_page(fbi->screen_buffer));

include/drm/drm_fb_helper.h

@@ -199,6 +199,8 @@ struct drm_fb_helper {
 	 * See also: @deferred_setup
 	 */
 	int preferred_bpp;
+
+	bool hint_leak_smem_start;
 };
 
 static inline struct drm_fb_helper *