drm/print: Improve drm_dbg_printer

With recent introduction of a generic drm dev printk function, we
can now store and use location where drm_dbg_printer was invoked
and output it's symbolic name like we do for all drm debug prints.

Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240517163406.2348-3-michal.wajdeczko@intel.comSigned-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/drm_print.c

@@ -217,8 +217,7 @@ void __drm_printfn_dbg(struct drm_printer *p, struct va_format *vaf)
 	if (!__drm_debug_enabled(category))
 		return;
 
-	/* Note: __builtin_return_address(0) is useless here. */
-	__drm_dev_vprintk(dev, KERN_DEBUG, NULL, p->prefix, vaf);
+	__drm_dev_vprintk(dev, KERN_DEBUG, p->origin, p->prefix, vaf);
 }
 EXPORT_SYMBOL(__drm_printfn_dbg);
 

include/drm/drm_print.h

@@ -175,6 +175,7 @@ struct drm_printer {
 	void (*printfn)(struct drm_printer *p, struct va_format *vaf);
 	void (*puts)(struct drm_printer *p, const char *str);
 	void *arg;
+	const void *origin;
 	const char *prefix;
 	enum drm_debug_category category;
 };
@@ -332,6 +333,7 @@ static inline struct drm_printer drm_dbg_printer(struct drm_device *drm,
 	struct drm_printer p = {
 		.printfn = __drm_printfn_dbg,
 		.arg = drm,
+		.origin = (const void *)_THIS_IP_, /* it's fine as we will be inlined */
 		.prefix = prefix,
 		.category = category,
 	};