Revert "drm/panel: Add device_link from panel device to DRM device"

linusw · atseanpaul · commit d6a77ba0eb92 · 2018-09-27T11:00:42.000-04:00
This reverts commit 0c08754. commit 0c08754 ("drm/panel: Add device_link from panel device to DRM device") creates a circular dependency under these circumstances: 1. The panel depends on dsi-host because it is MIPI-DSI child device. 2. dsi-host depends on the drm parent device (connector->dev->dev) this should be allowed. 3. drm parent dev (connector->dev->dev) depends on the panel after this patch. This makes the dependency circular and while it appears it does not affect any in-tree drivers (they do not seem to have dsi hosts depending on the same parent device) this does not seem right. As noted in a response from Andrzej Hajda, the intent is likely to make the panel dependent on the DRM device (connector->dev) not its parent. But we have no way of doing that since the DRM device doesn't contain any struct device on its own (arguably it should). Revert this until a proper approach is figured out. Cc: Jyri Sarha <jsarha@ti.com> Cc: Eric Anholt <eric@anholt.net> Cc: Andrzej Hajda <a.hajda@samsung.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Sean Paul <seanpaul@chromium.org> Link: https://patchwork.freedesktop.org/patch/msgid/20180927124130.9102-1-linus.walleij@linaro.org
diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
@@ -24,7 +24,6 @@
 #include <linux/err.h>
 #include <linux/module.h>
 
-#include <drm/drm_device.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_panel.h>
 
@@ -105,13 +104,6 @@ int drm_panel_attach(struct drm_panel *panel, struct drm_connector *connector)
 	if (panel->connector)
 		return -EBUSY;
 
-	panel->link = device_link_add(connector->dev->dev, panel->dev, 0);
-	if (!panel->link) {
-		dev_err(panel->dev, "failed to link panel to %s\n",
-			dev_name(connector->dev->dev));
-		return -EINVAL;
-	}
-
 	panel->connector = connector;
 	panel->drm = connector->dev;
 
@@ -133,8 +125,6 @@ EXPORT_SYMBOL(drm_panel_attach);
  */
 int drm_panel_detach(struct drm_panel *panel)
 {
-	device_link_del(panel->link);
-
 	panel->connector = NULL;
 	panel->drm = NULL;
 
diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
@@ -89,7 +89,6 @@ struct drm_panel {
 	struct drm_device *drm;
 	struct drm_connector *connector;
 	struct device *dev;
-	struct device_link *link;
 
 	const struct drm_panel_funcs *funcs;
 
