Commit 9521f9ba authored by Thomas Zimmermann's avatar Thomas Zimmermann
Browse files

drm/ast: Validate display modes against framebuffer and format limits 



Reimplement ast_mode_config_mode_valid() with DRM format helpers and
ast's helpers for framebuffer size calculation. Replaces ast's open-
coded assumptions on bpp and page-alignments.

Signed-off-by: default avatarThomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: default avatarJocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250324094520.192974-4-tzimmermann@suse.de
parent 23fd03aa

drivers/gpu/drm/ast/ast_mode.c

+15 −9
Original line number Diff line number Diff line
@@ -51,6 +51,8 @@ 


#define AST_LUT_SIZE 256



#define AST_PRIMARY_PLANE_MAX_OFFSET	(BIT(16) - 1)



static unsigned long ast_fb_vram_offset(void)

{

	return 0; // with shmem, the primary plane is always at offset 0
@@ -960,16 +962,20 @@ static const struct drm_mode_config_helper_funcs ast_mode_config_helper_funcs = 
static enum drm_mode_status ast_mode_config_mode_valid(struct drm_device *dev,

						       const struct drm_display_mode *mode)

{

	static const unsigned long max_bpp = 4; /* DRM_FORMAT_XRGB8888 */

	const struct drm_format_info *info = drm_format_info(DRM_FORMAT_XRGB8888);

	struct ast_device *ast = to_ast_device(dev);

	unsigned long fbsize, fbpages, max_fbpages;



	max_fbpages = ast_fb_vram_size(ast) >> PAGE_SHIFT;



	fbsize = mode->hdisplay * mode->vdisplay * max_bpp;

	fbpages = DIV_ROUND_UP(fbsize, PAGE_SIZE);



	if (fbpages > max_fbpages)

	unsigned long max_fb_size = ast_fb_vram_size(ast);

	u64 pitch;



	if (drm_WARN_ON_ONCE(dev, !info))

		return MODE_ERROR; /* driver bug */



	pitch = drm_format_info_min_pitch(info, 0, mode->hdisplay);

	if (!pitch)

		return MODE_BAD_WIDTH;

	if (pitch > AST_PRIMARY_PLANE_MAX_OFFSET)

		return MODE_BAD_WIDTH; /* maximum programmable pitch */

	if (pitch > max_fb_size / mode->vdisplay)

		return MODE_MEM;



	return MODE_OK;