Commit d6a77ba0 authored Sep 27, 2018 by Linus Walleij Committed by Sean Paul Sep 27, 2018

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



This reverts commit 0c08754b.

commit 0c08754b
("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

parent 337fe9f5

drivers/gpu/drm/drm_panel.c

+0 −10

Original line number	Diff line number	Diff line
		@@ -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;

include/drm/drm_panel.h

+0 −1

Original line number	Diff line number	Diff line
		@@ -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;

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