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

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Add device_link from panel device (supplier) to DRM device (consumer)
when drm_panel_attach() is called. This patch should protect the master
DRM driver if an attached panel driver unbinds while it is in use. The
device_link should make sure the DRM device is unbound before the panel
driver becomes unavailable.

The device_link is removed when drm_panel_detach() is called. The
drm_panel_detach() should be called by the consumer DRM driver, not the
panel driver, otherwise both drivers are racing to delete the same link.

Signed-off-by: Jyri Sarha <jsarha@ti.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/b53584fd988d045c13de22d81825395b0ae0aad7.1524727888.git.jsarha@ti.com
This commit is contained in:
Jyri Sarha 2018-04-26 11:07:00 +03:00 committed by Thierry Reding
parent 38992c57c9
commit 0c08754b59
2 changed files with 11 additions and 0 deletions
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10
drivers/gpu/drm/drm_panel.c
View File

@ -24,6 +24,7 @@
#include <linux/err.h>
#include <linux/module.h>
#include <drm/drm_device.h>
#include <drm/drm_crtc.h>
#include <drm/drm_panel.h>
@ -104,6 +105,13 @@ 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;
@ -125,6 +133,8 @@ 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

@ -89,6 +89,7 @@ struct drm_panel {
struct drm_device *drm;
struct drm_connector *connector;
struct device *dev;
struct device_link *link;
const struct drm_panel_funcs *funcs;