drm: WARN when calling drm_format_info() for an unsupported format
The format helpers have historically treated unsupported formats as part
of the default case, returning values that are likely wrong. We can't
change this behaviour now without risking breaking drivers in difficult
to detect ways, but we can WARN on unsupported formats to catch faulty
callers.
The only exception is the framebuffer_check() function that calls
drm_format_info() to validate the format passed from userspace. This is
a valid use case that shouldn't generate a warning.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1476744081-24485-5-git-send-email-laurent.pinchart@ideasonboard.com
diff --git a/drivers/gpu/drm/drm_fourcc.c b/drivers/gpu/drm/drm_fourcc.c
index 23d4b82..523ed91 100644
--- a/drivers/gpu/drm/drm_fourcc.c
+++ b/drivers/gpu/drm/drm_fourcc.c
@@ -102,15 +102,11 @@
}
EXPORT_SYMBOL(drm_get_format_name);
-/**
- * drm_format_info - query information for a given format
- * @format: pixel format (DRM_FORMAT_*)
- *
- * Returns:
- * The instance of struct drm_format_info that describes the pixel format, or
- * NULL if the format is unsupported.
+/*
+ * Internal function to query information for a given format. See
+ * drm_format_info() for the public API.
*/
-const struct drm_format_info *drm_format_info(u32 format)
+const struct drm_format_info *__drm_format_info(u32 format)
{
static const struct drm_format_info formats[] = {
{ .format = DRM_FORMAT_C8, .depth = 8, .num_planes = 1, .cpp = { 1, 0, 0 }, .hsub = 1, .vsub = 1 },
@@ -184,6 +180,26 @@
return NULL;
}
+
+/**
+ * drm_format_info - query information for a given format
+ * @format: pixel format (DRM_FORMAT_*)
+ *
+ * The caller should only pass a supported pixel format to this function.
+ * Unsupported pixel formats will generate a warning in the kernel log.
+ *
+ * Returns:
+ * The instance of struct drm_format_info that describes the pixel format, or
+ * NULL if the format is unsupported.
+ */
+const struct drm_format_info *drm_format_info(u32 format)
+{
+ const struct drm_format_info *info;
+
+ info = __drm_format_info(format);
+ WARN_ON(!info);
+ return info;
+}
EXPORT_SYMBOL(drm_format_info);
/**
diff --git a/drivers/gpu/drm/drm_framebuffer.c b/drivers/gpu/drm/drm_framebuffer.c
index 386977d..49fd7db 100644
--- a/drivers/gpu/drm/drm_framebuffer.c
+++ b/drivers/gpu/drm/drm_framebuffer.c
@@ -131,7 +131,7 @@
const struct drm_format_info *info;
int i;
- info = drm_format_info(r->pixel_format & ~DRM_FORMAT_BIG_ENDIAN);
+ info = __drm_format_info(r->pixel_format & ~DRM_FORMAT_BIG_ENDIAN);
if (!info) {
char *format_name = drm_get_format_name(r->pixel_format);
DRM_DEBUG_KMS("bad framebuffer format %s\n", format_name);