From: Linus Walleij <linus.walleij@linaro.org>
Date: Thu, 27 Sep 2018 14:41:30 +0200
Subject: Revert "drm/panel: Add device_link from panel device to DRM device"
Git-commit: d6a77ba0eb92d8ffa4b05a442fc20d0a9b11c4c4
Patch-mainline: v4.19-rc6
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166
This reverts commit 0c08754b59da5557532d946599854e6df28edc22.
commit 0c08754b59da
("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
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
drivers/gpu/drm/drm_panel.c | 10 ----------
include/drm/drm_panel.h | 1 -
2 files changed, 11 deletions(-)
--- 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 *p
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;
--- 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;