drm: deprecate driver date

The driver date serves no useful purpose, because it's hardly ever
updated. The information is misleading at best.

As described in Documentation/gpu/drm-internals.rst:

  The driver date, formatted as YYYYMMDD, is meant to identify the date
  of the latest modification to the driver. However, as most drivers
  fail to update it, its value is mostly useless. The DRM core prints it
  to the kernel log at initialization time and passes it to userspace
  through the DRM_IOCTL_VERSION ioctl.

Stop printing the driver date at init, and start returning the empty
string "" as driver date through the DRM_IOCTL_VERSION ioctl.

The driver date initialization in drivers and the struct drm_driver date
member can be removed in follow-up.
Reviewed-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Acked-by: Simon Ser <contact@emersion.fr>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240429164336.1406480-1-jani.nikula@intel.comSigned-off-by: Jani Nikula <jani.nikula@intel.com>

Documentation/gpu/drm-internals.rst

@@ -57,8 +57,8 @@ is larger than the driver minor, the DRM_IOCTL_SET_VERSION call will
 return an error. Otherwise the driver's set_version() method will be
 called with the requested version.
 
-Name, Description and Date
-~~~~~~~~~~~~~~~~~~~~~~~~~~
+Name and Description
+~~~~~~~~~~~~~~~~~~~~
 
 char \*name; char \*desc; char \*date;
 The driver name is printed to the kernel log at initialization time,
@@ -69,12 +69,6 @@ The driver description is a purely informative string passed to
 userspace through the DRM_IOCTL_VERSION ioctl and otherwise unused by
 the kernel.
 
-The driver date, formatted as YYYYMMDD, is meant to identify the date of
-the latest modification to the driver. However, as most drivers fail to
-update it, its value is mostly useless. The DRM core prints it to the
-kernel log at initialization time and passes it to userspace through the
-DRM_IOCTL_VERSION ioctl.
-
 Module Initialization
 ---------------------
 

drivers/gpu/drm/drm_drv.c

@@ -947,9 +947,9 @@ int drm_dev_register(struct drm_device *dev, unsigned long flags)
 	}
 	drm_panic_register(dev);
 
-	DRM_INFO("Initialized %s %d.%d.%d %s for %s on minor %d\n",
+	DRM_INFO("Initialized %s %d.%d.%d for %s on minor %d\n",
 		 driver->name, driver->major, driver->minor,
-		 driver->patchlevel, driver->date,
+		 driver->patchlevel,
 		 dev->dev ? dev_name(dev->dev) : "virtual device",
 		 dev->primary ? dev->primary->index : dev->accel->index);
 

drivers/gpu/drm/drm_ioctl.c

@@ -529,9 +529,10 @@ int drm_version(struct drm_device *dev, void *data,
 	version->version_patchlevel = dev->driver->patchlevel;
 	err = drm_copy_field(version->name, &version->name_len,
 			dev->driver->name);
+
+	/* Driver date is deprecated. Return the empty string. */
 	if (!err)
-		err = drm_copy_field(version->date, &version->date_len,
-				dev->driver->date);
+		err = drm_copy_field(version->date, &version->date_len, "");
 	if (!err)
 		err = drm_copy_field(version->desc, &version->desc_len,
 				dev->driver->desc);

include/drm/drm_drv.h

@@ -411,7 +411,7 @@ struct drm_driver {
 	char *name;
 	/** @desc: driver description */
 	char *desc;
-	/** @date: driver date */
+	/** @date: driver date, unused, to be removed */
 	char *date;
 
 	/**