drm/vkms/crc: Implement verify_crc_source callback

This patch implements "verify_crc_source" callback function for
Virtual KMS drm driver.

Changes Since V1:
- update values_cnt in verify_crc_source
Changes Since V2:
- don't return early from set_crc_source to keep behavior same (Haneen)

Cc: Haneen Mohammed <hamohammed.sa@gmail.com>
Signed-off-by: Mahesh Kumar <mahesh1.kumar@intel.com>
Reviewed-by: Haneen Mohammed <hamohammed.sa@gmail.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180821083858.26275-2-mahesh1.kumar@intel.com

drivers/gpu/drm/vkms/vkms_crc.c

@@ -70,6 +70,37 @@ void vkms_crc_work_handle(struct work_struct *work)
 	drm_crtc_add_crc_entry(crtc, true, crtc_state->n_frame, &crc32);
 }
 
+static int vkms_crc_parse_source(const char *src_name, bool *enabled)
+{
+	int ret = 0;
+
+	if (!src_name) {
+		*enabled = false;
+	} else if (strcmp(src_name, "auto") == 0) {
+		*enabled = true;
+	} else {
+		*enabled = false;
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+int vkms_verify_crc_source(struct drm_crtc *crtc, const char *src_name,
+			   size_t *values_cnt)
+{
+	bool enabled;
+
+	if (vkms_crc_parse_source(src_name, &enabled) < 0) {
+		DRM_DEBUG_DRIVER("unknown source %s\n", src_name);
+		return -EINVAL;
+	}
+
+	*values_cnt = 1;
+
+	return 0;
+}
+
 int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name,
 			size_t *values_cnt)
 {
@@ -78,10 +109,7 @@ int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name,
 	unsigned long flags;
 	int ret = 0;
 
-	if (src_name && strcmp(src_name, "auto") == 0)
-		enabled = true;
-	else if (src_name)
-		ret = -EINVAL;
+	ret = vkms_crc_parse_source(src_name, &enabled);
 
 	*values_cnt = 1;
 

drivers/gpu/drm/vkms/vkms_crtc.c

@@ -140,6 +140,7 @@ static const struct drm_crtc_funcs vkms_crtc_funcs = {
 	.enable_vblank		= vkms_enable_vblank,
 	.disable_vblank		= vkms_disable_vblank,
 	.set_crc_source		= vkms_set_crc_source,
+	.verify_crc_source	= vkms_verify_crc_source,
 };
 
 static void vkms_crtc_atomic_enable(struct drm_crtc *crtc,

drivers/gpu/drm/vkms/vkms_drv.h

@@ -125,6 +125,8 @@ void vkms_gem_vunmap(struct drm_gem_object *obj);
 /* CRC Support */
 int vkms_set_crc_source(struct drm_crtc *crtc, const char *src_name,
 			size_t *values_cnt);
+int vkms_verify_crc_source(struct drm_crtc *crtc, const char *source_name,
+			   size_t *values_cnt);
 void vkms_crc_work_handle(struct work_struct *work);
 
 #endif /* _VKMS_DRV_H_ */