drm: Print pretty names for pixel formats

Rather than just printing the pixel format as a hex number, decode the
fourcc into human readable form, and also decode the LE vs. BE flag.

Keep printing the raw hex number too in case it contains non-printable
characters.

Some examples what the new drm_get_format_name() produces:
DRM_FORMAT_XRGB8888: "XR24 little-endian (0x34325258)"
DRM_FORMAT_YUYV: "YUYV little-endian (0x56595559)"
DRM_FORMAT_RGB565|DRM_FORMAT_BIG_ENDIAN: "RG16 big-endian (0xb6314752)"
Unprintable characters: "D??? big-endian (0xff7f0244)"

v2: Fix patch author

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 27 insertions, 2 deletions

diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index e7e92429d10f..079996ad02a7 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -29,6 +29,7 @@
  *      Dave Airlie <airlied@linux.ie>
  *      Jesse Barnes <jesse.barnes@intel.com>
  */
+#include <linux/ctype.h>
 #include <linux/list.h>
 #include <linux/slab.h>
 #include <linux/export.h>
@@ -252,6 +253,28 @@ char *drm_get_connector_status_name(enum drm_connector_status status)
 }
 EXPORT_SYMBOL(drm_get_connector_status_name);
 
+static char printable_char(int c)
+{
+        return isascii(c) && isprint(c) ? c : '?';
+}
+
+char *drm_get_format_name(uint32_t format)
+{
+        static char buf[32];
+
+        snprintf(buf, sizeof(buf),
+                 "%c%c%c%c %s-endian (0x%08x)",
+                 printable_char(format & 0xff),
+                 printable_char((format >> 8) & 0xff),
+                 printable_char((format >> 16) & 0xff),
+                 printable_char((format >> 24) & 0x7f),
+                 format & DRM_FORMAT_BIG_ENDIAN ? "big" : "little",
+                 format);
+
+        return buf;
+}
+EXPORT_SYMBOL(drm_get_format_name);
+
 /**
  * drm_mode_object_get - allocate a new modeset identifier
  * @dev: DRM device
@@ -1834,7 +1857,8 @@ int drm_mode_setplane(struct drm_device *dev, void *data,
                 if (fb->pixel_format == plane->format_types[i])
                         break;
         if (i == plane->format_count) {
-                DRM_DEBUG_KMS("Invalid pixel format 0x%08x\n", fb->pixel_format);
+                DRM_DEBUG_KMS("Invalid pixel format %s\n",
+                              drm_get_format_name(fb->pixel_format));
                 ret = -EINVAL;
                 goto out;
         }
@@ -2312,7 +2336,8 @@ static int framebuffer_check(const struct drm_mode_fb_cmd2 *r)
 
         ret = format_check(r);
         if (ret) {
-                DRM_DEBUG_KMS("bad framebuffer format 0x%08x\n", r->pixel_format);
+                DRM_DEBUG_KMS("bad framebuffer format %s\n",
+                              drm_get_format_name(r->pixel_format));
                 return ret;
         }