drm/sched: Define pr_fmt() for DRM using pr_*()

Define pr_fmt() as "[drm] " for DRM code using pr_*() facilities, especially
when no devices are available. This makes it easier to browse kernel logs.
Signed-off-by: Luben Tuikov <ltuikov89@gmail.com>
Acked-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231110002659.113208-2-ltuikov89@gmail.com

include/drm/drm_print.h

@@ -26,6 +26,20 @@
 #ifndef DRM_PRINT_H_
 #define DRM_PRINT_H_
 
+/* Define this before including linux/printk.h, so that the format
+ * string in pr_*() macros is correctly set for DRM. If a file wants
+ * to define this to something else, it should do so before including
+ * this header file.
+ *
+ * It is encouraged code using pr_err() to prefix their format with
+ * the string "*ERROR* ", to make it easier to scan kernel logs. For
+ * instance,
+ *   pr_err("*ERROR* <the rest of your format string here>", args).
+ */
+#ifndef pr_fmt
+#define pr_fmt(fmt) "[drm] " fmt
+#endif
+
 #include <linux/compiler.h>
 #include <linux/printk.h>
 #include <linux/seq_file.h>