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

This reverts commit 0c08754b59.

commit 0c08754b59
("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
This commit is contained in:
Linus Walleij 2018-09-27 14:41:30 +02:00 committed by Sean Paul
parent 337fe9f5c1
commit d6a77ba0eb
2 changed files with 0 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
drivers/gpu/drm/drm_panel.c
View File

@ -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;

1
include/drm/drm_panel.h
View File

@ -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;