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

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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: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Jocelyn Falempe <jfalempe@redhat.com>
Link: https://lore.kernel.org/r/20250324094520.192974-4-tzimmermann@suse.de
This commit is contained in:
Thomas Zimmermann
2025-03-24 10:44:11 +01:00
parent 23fd03aa6c
commit 9521f9ba82
1 changed files with 13 additions and 7 deletions
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20
drivers/gpu/drm/ast/ast_mode.c
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@@ -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;
unsigned long max_fb_size = ast_fb_vram_size(ast);
u64 pitch;
max_fbpages = ast_fb_vram_size(ast) >> PAGE_SHIFT;
if (drm_WARN_ON_ONCE(dev, !info))
return MODE_ERROR; /* driver bug */
fbsize = mode->hdisplay * mode->vdisplay * max_bpp;
fbpages = DIV_ROUND_UP(fbsize, PAGE_SIZE);
if (fbpages > max_fbpages)
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;